THE this of a certainty would have taken place TH RAIN IN THE BRITISH ISLES. HE seventh annual statement of British rainfall has just been issued by Mr. G. MECHANICS' MAGAZINE. they were attached to wooden ships, to the J. Symons. It commences with the sentence, TH LONDON: FRIDAY, APRIL 12, 1867. great detriment of the iron. But from general | "As rainfall work makes yearly more real ignorance of the exact nature of galvanic ac-progress, there is (perhaps consequently) less tion this danger has been greatly and unneces- apparent progress to note." This assertion sarily exagerated: still, in itself, the danger appearing somewhat paradoxical we endeais great enough. To avoid this danger all voured at once to learn what the real progress A RETROSPECTIVE GLANCE AT THE manner of expedients have been suggested. has been. We have only been able to find, It has been suggested to coat the hull of the however, much the same statements of the FOULING AND CORROSION PROBLEM. ship first with wood, and then to proceed as progress of his work that Mr. Symons has HE art of coating metals with metals is with a wooden ship. Marine glue and gutta made for the past three or four years, so we now pretty well understood in its gene-percha have also been suggested, to form a pass on to other considerations. In the MEral bearing, but as to its application to par- sort of cement by which the thin sheets of CHANICS' MAGAZINE, May 18, 1866, in an article ticular cases many difficulties present them- copper might be cemented to the ship, but on rain gauges, it was argued that they should selves. There is one of its applications in many practical difficulties suggested them- not be constructed with receivers less than various forms which now and for some time selves, stich as the means of putting the sheets 8in. in diameter; because, theoretically it can past has attracted much attention-namely, on by heat, and to their adhesion when on; be proved that the same error in the diameters the coating of iron with some other metal, so in fact, none of these were more than sugges- of different sized gauges will occasion the that it may be protected not only from tions. Another plan was that of putting on to largest percentage in the amount of rainfall the chemical action of sea water, but also the iron direct, by means of screws, sheets of measured by the smallest gauges, and practifrom the adhesion of such plants and animals zine; zinc being positive to iron, the action cally gauges of less diameter than 8in., even as have their natural conditions of existence would be all on the zinc, and this is correct as when accurately made, are found to give a deon rocks or other substances, which are far as corrosion is concerned, but fouling was ficient measurement. Accordingly objection accidentally found in sea water. This has lost sight of, and gradually it has become appa- was made to the employment of 5in. gauges been a question gradually growing into rent that there was nothing but copper or so persistently advocated and so largely emimportance since the first substitution of some alloy of copper which would thoroughly ployed by Mr. Symons. His statement of iron for wood in the construction of protect an iron ship from both corrosion and British rainfall in 1866 shows that he fully inships, and now has become one of na- fouling, as copper had been previously sug- tends to follow his own devices. In compiling tional importance. At first, but little was gested, with an isolating coating between it tables of monthly rainfall he has excluded all thought of it, whether as to its necessity or as and the iron, and abandoned. results arrived at with any other than 5in. to the difficulty of performing the operation gauges. Notwithstanding his reiterated asserif required. But gradually the necessity for tion, "I had no preconceived theories or fancies some preservative became apparent; for not to support," it is evident that he intends to only were some of the plates used in the make himself conspicuous by differing from construction of the skin of iron ships found the opinions and practice of the best meteoroto be seamed and corroded into deep pits logical observers. Mr. Glaisher, a meteoroloin a very short time, but on the bottoms of gist of the greatest experience, declares that all such ships seaweed and barnacles were he can trust the results of no rain gauge less found to grow in such abundance that they than 8in. in diameter; and the oldest and most reduced the speed of many ships to one experienced observers all use the gauge dehalf. Such disasters caused many at signed by him. first to doubt whether it would be expedient to continue to build ships of iron, as there were many and almost insuperable difficulties to their protection, which did not exist with regard to wood. Wood could be easily protected from the teredo, seaweed, and barnacles by a thin sheet of copper or Muntz's metal being nailed on to it, but such a simple method was not possible with iron. Here was a difficulty, and to combat it hundreds of inventors and quasi-inventors rushed into the field. Hundreds of metallic paints were suggested and patented, and even several varieties of grease and soap. Still the difficulty was not overcome. The barnacles would adhere to the paint, and the grease and the soap were of no avail. Zinc was suggested as a coating. It was known that a thin film of oxide on zine would thoroughly protect it from any further atmospheric action, and also from the action of ordinary water. Experiments were made to ascertain the effects of sea water upon it, and it was found that these effects, extended over even considerable periods, were almost nil; therefore it was proposed to zinc or galvanise the plates used for building ships. Copper as a directly adhesive coating to the plates of iron is the last method that has been proposed. Leaving out of the things proposed the copper coating to be put on to the iron plates by heat or fusion, as impracticable, there was nothing left but the electrolytic process. To deposit a coating of copper on iron is easy, but to deposit a thoroughly adhesive coating of copper on iron is not so easy, as all know who have attempted it. To get a perfectly adhering coating the iron must be perfectly pure, but even an approximation to purity is The returns from Calne, by Colonel Ward, almost impossible in commercial iron; confirm the argument which was based upon secondly, to get a solution of copper wherein his figures last year; and, generally, Mr. Syiron is neutral or nearly so, which is easy, and mons has failed to prove, although he has lahas been obtained and used for more than boured to do so, that the small gauges, even twenty years-namely, the cyanide of copper when correctly made, give true indications of in a solution of cyanide of potassium, and the the rainfall. As his limited experience canlast patent for this purpose seems to be just not be better than that of Mr. Glaisher and the this process, which has been used for copper- observers who have used the 8in. gauge for the ing small articles of iron for the last twenty last quarter of a century, he should have acyears, with this addition, that the iron is first quiesced in what had been satisfactorily settled made positive by means of a current of elec- by his predecessors, unless he could have shown tricity before receiving the deposit of copper. them to have been in error. Previous to the But this is no advantage; the iron will be still employment of 5in. gauges by Mr. Symons's as impure after a small portion has been dis-observers, 8in. was considered by meteorosolved from it by the positive current of elec-logists the minimum size, and should still tricity as it was before; nay, there will be an be so regarded. In a paper by the Rev. T. accumulation of impurities on the surface E. Crallan on rain-gauge experiments, printed which were in the metal dissolved, as in Mr. Symons's recent pamphlet, it is very is always the case with plates of commercial justly stated, that "In order to arrive at any copper when used as positive depositing just and true deductions from the observations plates. This coating can be no more adhesive of rainfall, it is of course first and absolutely than the old cyanide coating was, and if put necessary that the observations themselves on strictly in accordance with this addition, should approach as near as possible to correctnot so adhesive. But there is a method of ness. To arrive at this desirable state of putting copper on to iron which will stand a things, it seems imperative to eliminate all red heat, by first depositing a coating of pure sources of error, and arrive at tables for corThis might have been done, and it would iron from a solution of ferrocyanide of potas-rection, for altitude, magnitude, and such certainly have protected the ship from sium with other salts to prevent oxidation of other differences as may occur, so as to bring corrosion by seawater, if properly carried out; the solution. Still, though this be done, the diffi- all observations to the same uniform standard. but it would not have prevented the ad- culty is not solved; the plates have to be riveted The observations made and making at Calne hesion of seaweed or barnacles, which is onto the frame of the ship; and here, if the rivets and other stations, as to magnitude and elevaof the two evils perhaps the greater. It be of copper, they will not be strong enough, tion, will, it is to be hoped, tend much to eluwas suggested that though the plates might and if they be of iron coated with copper, the cidate these points. There will still remain be cut and drilled for the rivets, and ready to be copper will bruise off in riveting. Appa- to be settled the points of comparison of maput on before being zinced, there would be the rently the only method which is likely to terials, and of evaporation from different gauges rivet heads exposed after riveting down, which succeed is a modification of some of the pro- of different constructions, and the effect of would cause galvanic action to be set up, and cesses proposed-viz., sheets of copper, or an daily as compared with monthly reading." It as the iron rivet heads would be negative to alloy of copper put on with screwed rivets, with is lamentable to think that all this complexity the zinc, the zinc would be soon all corroded off. tarred felt between the copper and the iron. might have been avoided, at least in a great But this, of course, could have easily been Such a process has been proposed to the measure, by adherence to a uniform pattern avoided by zincing the rivets and riveting Government, but they have not yet seen their of gauge, and none answers better than Mr. them inside; nevertheless, the zincing of ship's way to a trial of it. In giving this sketch of Glaisher's. "It is, in fact, very desirable, if plates has not been tried. Copper would have the fouling and corrosion problem we have possible, to arrive at some gauge which from been at once attached to the bottoms of ships designedly omitted the names of the authors a combination of form, size, construction, and in imitation of the sheathing of wooden ships of each process, as we do not wish to excite material, should as nearly as possible give us had it not been for the fear of galvanic action any jealousies in the matter, but just to indi-a correct measure of the amount of rainfall being set up between the copper of the sheath-cate what has been done towards the solving ing and the iron of the skin of the ship, and of this difficult but important problem. upon the earth's surface, and to determine, if possible, the corrections required to reduce ob servations with the various forms of gauge statements. There cannot be any question as something considerable. In the accompanying hitherto used to their true valves. At the present moment we have so many different constructions, sizes, materials, and altitudes, that the results from them all cannot be depended on as giving comparable results for different localities." We entirely concur with Mr. Crallan. Mr. Symons says:- "I feel almost certain that roof observations are hopelessly unreducible. Where they have been continued for a length of time I would not recommend their abandonment, because they are useful for giving the secular variation from year to year, but they are no guide to the fal on the ground, and are not comparable one with another. Gauges on or attached to walls seem more hopeful, because it appears probable their indications depend solely on these conditions: elevation, elevation above the wall, angle which the wall makes with the plane of the meridian. These are definite points, each capable of direct determination, and therefore I do not despair, though always extremely sorry to find a rain gauge either on a roof or a wall, in fact, anywhere but on or in the ground." Here, again, unless a rigid adherence to position and exposure be made, the variety of circumstances to be taken into consideration must render the subject of rainfall exceedingly complicated, and certainly it is enough to make anyone despair who attempts to investigate it. From observations made by Mr. Chrimes at Rotherham, on the amount of rain caught by a peculiarly constructed gauge, having receivers placed vertically as well as horizontally, it appears that when the mean daily velocity of the wind, on days with rain, was about 100 miles, the rain fell at an angle from the vertical of about 30 deg., and a gauge 25ft. above the ground caught 6 per cent. less rain than a gauge on the ground; with velocity 150 miles, the inclination was 40 deg., and the percentage 12 less; with velocity 180 miles, the inclination was 50 deg. and percentage 17 less. These results are curious, as showing the influence of the wind's velocity on the inclination of showers, and on the less amount of rain collected by gauges raised above the ground in open places. | to the practical value of the work which he has A' SCREENING SAND. PROPER description of sand constitutes a more important ingredient in the composition of a good mortar than is usually admitted; and even when its value is fully recognised too little attention is often paid to its quality. There are certain localities in which good sand is always to be found, and again there are others which are entirely destitute of the least trace of it. Sometimes it can also be procured in a state fit for using immediately, but as a general rule it requires to be screened. In specifications it should be described as clean and sharp, free from all dirt, vegetable substances, and other impurities. The simplest method, and the one always practised by practical men to distinguish a clean sand, is to take up a handful, squeeze it well, and then observe whether it comes readily off the palm, which it will not do, if there be any very perceptible The comparison of the rainfall of 1866 with amount of dirt or loam mixed with it. Whether the average of 1860-65 is interesting. Mr. it is that we use different proportions, different Symons tells us, in England everywhere the ingredients, or no longer possess the same total was above the average-on the whole quality of sand and lime comprising the morabout 19 per cent.; in Scotland, the excess on tars of early times, it is certain that there is the whole only amounted to 4 per cent. ; and no comparison between them and ours. It in Ireland, while the fall was above the aver- has been suggested that the inferiority of age in the west, it was below in the east. 1866 modern mortar is due to the presumption that was a wet year, but not so wet as 1860 or the ancients had some peculiar plan of pre1852 or 1848. We select, as representing the paring their lime, the secret of which has been distribution of rain in the British isles, the lost. Be this as it may, it is unquestionable total amounts collected in 1866, at the follow-that, considering the rapid manner in which ing places, all of which are at or about 100ft. buildings, railway viaducts, and other struc. above the sea:-London, 30.5in. on 192 days; tures are now run up, there is more than ever Southampton, 42in. on 199 days; Cardington, a necessity for employing good mortar. The Beds, 26.9in. on 184 days; Penzance, 48.5in.; condition in which building sand is generally Plymouth, 53in.; Bristol, 39.7in. on 205 days; found is that of gravel, which on being screened Ross, Hereford, 37.2in. on 191 days; Eve- yields sand suitable for making mortar, and sham, Worcester, 33·lin. on 210 days; Gate ballast for mixing with lime to form concrete. Burton, Lincoln, 25.5in., and Market Rasen, The weight of the unscreened gravel has been 32.8in.; Beeston, Nottingham, 28.1in.; Man- found by actual experiment to be 25 cwt. per chester, 43.2in. on 196 days; Lancaster, 57in. cube yard; that of the ballast when screened on 155 days; Leeds, 35in. on 169 days; Scar- 25 cwt., and that of the screened sand 21 cwt. borough, 31.4in. on 221 days; Seaham, 28.3in. per cube yard. When these weights were on 154 days; Workington, 39.5in. on 195 taken, the material was perfectly dry, and the days; Carlisle, 27.5in. on 182 days; Tynant, box was filled loosely in the same manner that Glamorgan, 59in. on 232 days; Llandudno, a cart would be, without any ramming or Denbigh, 33.6in. on 178 days; Annan, 43 2in. pumming to make the substance pack tighter. on 199 days; Prestonkirk, 22.7in. on 173 A cube yard in the solid before excavation days; Loch Lomond, 110in.; Islay, 80.6in.; would weigh a good deal more than the above, Tyree, Argyll, 44.6in. on 239 days; Dun- and would in all probability come near to 30 blane, Perth, 32.8in.; and Auchterarder, cwt., especially if wet. 42.6in.; Aberdeen, 29in. on 239 days; Inverness, 26.1in. on 170 days; Monkstown, Dublin, 28in. on 218 days; Fermoy, Cork, 37.3in. on 229 days; Letterkenny, Donegal, 61.9in. We gladly record that Mr. Symons has improved his lists by inserting a column for the diameter of the gauges used; and that it is much better printed than his former yearly cuts we give an elevation and section of an A a its exterior surface there is a cylinder H enclosing a spring working upon an axis. One end of this axis is connected with the forked branch h bent round to avoid the leg C' as is well represented fig. 2. The hopper also contains a movable table G, which can be adjusted to any angle by the rod 1, which carries at its lower extremity a fork n catching the crooked branch h (see fig. 1). This latter is FIC.I. E The size of the meshes, or rather the distance between them in the screens, will vary accordingly, as fine mortar for face work and neat joints, or coarse for backing and rough work is required. For gravel to be well screened there should not be less than four meshes to the inch, and the great point is to get all the sand screened in fine weather and when dry, for the difference in a large quantity would be furnished with a series of holes, and the angel of inclination of G is determined accordingly as the pin passing through the eye of n is inserted in one or other of them. A glance at fig. 1 will point out that the workman stands in a position relative to the screen exactly the reverse of what usually occurs. In this instance he stands behind the apparatus and not in front of it. He throws the sand against the back k of the hopper and it falls upon the movable table G. So soon as a certain weight is placed upon G, the spring in the cylinder H uncoils and the table drops, allowing the accumulated material to fall upon the meshes of the frame B, through which the smallest particles at once pass. Manifestly, however, the impetus acquired by the descent from the table G to the screen would not be sufficient to cause the greater portion of the sand to pass through. In the ordinary screen the labourer throws the sand with some violence against the wires; in the majority of cases with a great deal too much violence, as the broken and enlarged meshes of many a screen can testify. Something, therefore, in addition to the mere fall of the sand upon B is required to accomplish the operation successfully, and in this consists the ingenuity of M. Fournier. Directly SIX NOTICES OF BOOKS. The work, however, has been carefully re IXTEEN years since a series of experi-vised, and, as in the opinion of our leading ments were made in Paris to test the astronomers, the mean equatorial horizontal efficiency of certain telegraphic apparatus. parallax of the sun has now been authoritaA continuous wire was laid from Paris to Lille tively increased from 8" 5776 to 8" 94, imand back, making a length of 366 miles. To portant numerical corrections have been made this was added another length of wire, which throughout the volume. The work is illusbrought the whole length up to 1,082 miles, trated with numerous well executed drawings A message of 282 words was then transmitted on wood and stone; among the most prothrough the wire from one end, while at the minent of which are charts of the moon, and other end was a pen which wrote the message re presentations of most of the important asmechanism. This was regarded as a wonder- appendix is added, in which will be found on a sheet of paper moved under it by simple tronomical instruments of the day. A useful ful feat at the time, but since then the science notes of the principal recent astronomical of telegraphy has made such wonderful pro- researches. The various sections of the scigress that at the present time the two Atlantic ence are so arranged by Mr. Dunkin, as to cables when joined end to end so as to form exhibit the various movements and physical one unbroken length of nearly 4,000 miles, peculiarities of the different members of the can readily be worked at a speed far greater solar system, without the aid of mathematical than through the comparatively small length symbols, and thus the work is eminently of line used in the foregoing experiments. adapted for students who otherwise might fail Each cable can easily pass fifteen words per in the study of this science. minute, or upwards of forty average messages first volume of Richardson and Watts's "CheIn chemistry we have the fifth part of the per hour between Europe and America. In short land lines this rate of transmission is mical Technology," which is now going greatly exceeded. Of course to bring this to through a second edition. This part compass great changes have taken place in the pletes the series of volumes devoted to the the table G is freed from the weight upon it, whole system of telegraphy, which, compara-/ acids, alkalies, and salts, and embraces the the spring raises it again smartly to its original tively speaking, was but in its infancy when chemical technology of what the authors term position, and in so doing quickly raises the the experiments to which we have alluded took "the organic acids." The first appendix crooked branch h, which had been depressed place. In the same state, too, was this contains the results of recent researches and by the action of the spring as already ex-science when Dr. Lardner some thirteen years of the latest improvements connected with plained. The branch h in rising strikes against since brought out the first edition of his treat- these manufactures. An abstract of all the the rod P, which in its turn communicates a ise on the electric telegraph. Inventions which patents connected with the same manufactures strong shaking motion to the screen, causing then were considered of the highest importforms the second appendix, whilst the third the remaining smaller particles to escape ance have since grown obsolete, and the tele- comprises the various chemical tables referred through the meshes to the ground, and the graphic appliances of the time have mostly to throughout the work. It also includes Mr. larger to roll down to the lower end of the been superseded by others not then thought salts which will doubtless be found of great apparatus where they may be received into a of. It is therefore with much pleasure we suitable receptacle. One advantage of this welcome a new edition of Dr. Lardner's practical utility. The concluding appendix arrangement is obviously that a second shift- treatise, which has been revised and recontains copies of various reports and other ing of the coarser particles or ballast is saved, written by Mr. Edward B. Bright. documents relating to the Patent Laws, and as it can be carried away in the mass, and the Mr. Bright assisted Dr. Lardner in preparing which have a bearing upon their improvement. sand only remains to be shovelled up again. the first edition, and we may congratulate the It is of the highest importance in the present sticky the table G and the spring may be dis- the present instance. As the descriptions con- should be well versed in the chemistry of his Unless the material to be screened is damp or latter on having the services of the former in day when the practical application of chemistry is universal, that every manufacturer pensed with, and the operation conducted as tained in the previous editions could not con- business. This being admitted, it will readily in the ordinary manner, by simply throwing vey any adequate idea of the present progress be perceived that such a book as the present it into the hopper, although the position of the of telegraphic apparatus it became necessary should find a place with all those connected screener is still reversed. many new topics have been introduced, and, with the arts and manufactures, who wish to amongst others are the practical points relating keep pace with the times. To name the manuROFESSOR KICK of the Polytechnic the Malta and Alexandria, and other im-sufficient to indicate their importance; but to to the Atlantic telegraph, the line to India, factures described in these volumes would be Institution of Prague, has recently pub-portant submarine cables. We notice, too, mar it still further, we give the following lished in Dingler's Journal a very ingenious that the important question of railway train values of a few of the chemical manufactures method of preparing lecture diagrams. He signalling is specially dealt with, the applied imported or produced in this country. For takes ordinary drawing paper, or, still better, inventions of Mr. Preece and others being fully instance, in sait we have an annual weight of stout brown paper, and having stretched it on described. The transmission of time, weather 1,570,972 tons, which at 10s. per ton, gives a drawing board coats it with a thin glue with observations, and storm warnings by the elec. £785,486. Then the soda manufacture gives which is mixed a certain quantity of lamp tric telegraph are also treated of, and the im- £2,500,000, whilst carbonate, nitrate, and black and powdered pumice stone. The soluother portance of the invention as applied to these salts of potash give, £873,670. tion should be of a syruppy consistence, and purposes is fully shown. The book indeed Soap shows 200,000 tons, which at £28 per should only contain glue enough to prevent gathers up every practical point, and con- ton, produces £5,600,000; and grease for use the lamp black rubbing off without rendering cumstance in connection with telegraphy, and in locomotives, carts, waggons, and mining, the surface shining. The pumice stone is for the author explains the whole matter in a yields us £348,165 annually. The work bethe purpose of giving a better hold to the popular, and at the same time in a condensed fore us, which is fully illustrated, embodies chalk with which the drawing is made. Two form. The treatise is accompanied by 140 matter from the pens of several of the leading coats will generally be enough to give the illustrations, which, taken as adjuncts to the chemists of the day, or the results of many of paper the required depth of colour. The diagram is now sketched in French chalk, and reader with the various telegraphic apparatus. text, are extremely useful in familiarising the the whole, is one of the most valuable works their most important investigations, and, on when complete, the lines are to be gone over Mr. Bright has done the public good service in connection with the science of applied PR CHEAP LECTURE DIAGRAMS. to remodel and rewrite the work. Hence in thus gathering up the whole science of with ordinary chalk. The superfluous dust Cooke's chart of the solubilities of different chemistry. The last part of Mr. Watts's dictionary of chemistry contains the concluding portion of his interesting article on sodium, and conincludes an able article on "Specific Gravity," tinues on to the article "Stilbite." It by Mr. C. G. Williams, in which the author the methods of determining the specific graviconsiders in detail and under separate heads ties of solids, liquids, vapours, and gases. The article is well illustrated with engravings, obtaining specific gravities under different showing the various apparatus required in "Chemical Technology; or, Chemistry in its Applicacations to the Arts and Manufactures." BY THOMAS RICHARDSON, M.A., F.R.S., &c., and HENRY WATTS, B.A., F.R.S., &c. London: H. Baillière, 219, Regent-street, 1867. + Handbook of Astronomy. By DIONYSIOUS LARDNER, "A Dictionary of Chemistry, and the Allied Branches D.C.L. Third Edition. Revised and Edited by EDWIN of other Sciences." BY HENRY WATTS, B.A., F. C. S., &c., street, 1867. DUNKIN, F.R.A.S. London: James Walton, 137, Gower-assisted by eminent contributors. Part XXXVIII, London: Longmans and Co. 1867. conditions. It also gives the methods adopted 220°C Faint yellow Straw, yellow Surgicalinstruments. 230 255 265 Purple spots 277 Purple 288 Pale blue 293 Dark blue 316 Blackish blue These One by one the objections to its employment and removal of the unstable comhave been removed, and the difficulties that pounds. stood in the way have been overcome. Its The power of charcoal to absorb, condense, manufacture of equal quality is now as much and change gases and vapours is well known. a matter of certainty as that of gunpowder; Now changes produced in the pores of the its liability to decomposition is completely charcoal are described in general terms as the obviated; and the rapidity of its combustion result of oxidation, but what actually takes can be accurately regulated. All this has place is known but in a few instances. The been done by the combined exertions of subject has been further elucidated by a Major Von Lenk, of the Austrian army, Mr. chemist, who sent a paper but forgot to send Abel of Woolwich, and the Messrs. Prentice his name to the Chemical Society. This of Stowmarket. It would be unfair not to gentleman experimented with boxwood charmention that the chemical constitution of coal, which after ignition was placed in gun cotton was accurately determined by a oxygen gas. After it was saturated with this very able chemist lately deceased, Mr. E. gas it was placed in other gases and vapours, A. Hadow, of King's College. Mr. Abel, in a the absorbtion was noticed, and the resulting communication to the Royal Society last year products extracted and examined. In this way completely confirmed Mr. Hadow's view, it was proved that moist sulphurous acid and and on that point there can be no further dis- also sulphuretted hydrogen were changed to pute. Mr. Abel has since occupied himself sulphuric acid; common alcohol to acetic acid, with a study of the causes which lead to and amylic alcohol to valerianic acid. The spontaneous changes in the material, and the result with methylic alcohol was doubtful, but conditions which favour them; and this was probably formic acid was produced. the subject of his last communication. In the are all instances of direct oxidation, and clearly early days of the manufacture before the com- show what would happen in a great number position was understood, and the conditions of cases. The author mentioned, that necessary to ensure constancy were not contrary to what might have been expected, known, two disastrous explosions, one in this and indeed has been asserted, ammonia does country and one in France, occurred, which not undergo oxidation in the pores of charcoal. were undoubtedly the result of spontaneous The condition in which oxygen exists in the changes. A close investigation of the causes charcoal and which gives it so much chemical which lead to these changes became therefore activity was the subject of some discussion. In architecture we have a new edition of a necessity before full reliance could be It is commonly supposed to be liquified on the Gwilt's "Encyclopædia of Architecture,* placed on gun cotton. It is highly satisfactory surface; but Mr. De la Rue pointed out that which has been very carefully revised by Mr. to find that such an investigation has lead to the amount of condensation which actually Wyatt Papworth, who has introduced many the discovery of a simple means of preventing takes place only represents a pressure of about judicious alterations and additions. This decomposition. Tri-nitro-cellulose, the most half a ton on the square inch, a weight that valuable work was first published in 1842, and explosive, and we may say perfect form of gun must fall very short of compressing oxygen to has since passed through four impressions. It cotton, is not liable to decomposition. But a liquid. It may be, however, that there is has now undergone a thorough revision, and even in the best mode of conducting the not a complete analogy between the compreshas been accommodated to the present time. manufacture, such as we shall fully describe in sion caused by the application of mechanical The history of Pointed architecture has been an early number, it seems impossible to pre- force, and the condensation that takes place entirely re-written, and in the Theoretical vent the formation of a very small amount in porous bodies. division of the work many of the sections-not more than two per cent. of the lower have been almost wholly re-written, and include the progress of information on the sub. jects to which they refer. The profession of the engineer is becoming more and more in separably united with that of the architect, so that it becomes necessary to combine engineering with architectural information. Recognising this necessity, Mr. Papworth has judiciously introduced the results of recent inquiries into the strength of beams, girders, and columns, both of timber and iron. It thus follows that the student will be relieved of much perplexity which he has hitherto encountered in studying the works of the several authors who have written on the subject. At the same time it will prepare him for the further study of the higher scientific development of those works. In the section relating to practical architecture considerable additions have also been made, a chapter on Medieval architecture having been added. To the present edition Mr. Papworth has prefixed a memoir of Mr. Gwilt, which will be read with interest by all architects. The book is beatifully illustrated with more than eleven hundred engravings on wood, and to show the extent of the additions we may mention that nearly five hundred engravings have been added in the present volume, which ought to be found in the hands of every architect upon commencing his career. forms of nitro-cellulose which are prone to Captain le Guen has made experiments on the manufacture of tungsten steel by Bessemer's process. The process was conducted in the ordinary way, grey Scotch pig and some Spiegeleisen being employed; but in the convertor was added a quantity of iron containing a known weight of tungsten. This would have given 0.7 per cent. of tungsten in the whole mass, but one half was lost by oxidation in the convertor. Thus the amount of tungsten in the steel was excessively small, nevertheless it received a good temper, forged, and rolled well. Whether this could be ascribed to the tungsten may be doubtful, but the author expresses an opinion that ordinary grey ironnot at all steely and rather impure may by the addition of tungsten be converted into good steel by Mr. Bessemer's method. Material for paper making is still scarce, so we call attention to the fact that very successful experiments have been made in France with the deep root of Lucerne. This possesses a strong fibre and yields 56 per cent. of pulp, a considerably larger proportion than straw. It is treated in the same way as straw, boiled with caustic soda, and bleached with chloride of lime; and the paper when finished is said to be very soft, white, and beautiful. The first result of change is the production of a little nitrous acid. Favoured by the presence of heat and moisture, the change if unchecked will then proceed, until as a final result the cotton is converted into a gum-like mass, of which oxalic and pectic acids are the principal ingredients, a considerable evolution of gas-nitrogen, nitric oxide, and some nitric acid-having in the meantime taken place. Now if the change be arrested at the first stage (the formation of a little nitrous acid) it is found that all further decomposition is completely prevented. The first observation made was, that washing the cotton in a hard water rendered it permanent. The explanation of this was that a quantity of carbonate of lime became deposited in the cotton, which A discharge easy of application has been neutralised the nitrous acid as soon as formed. wanted by the printers for the aniline dyes. Von Lenk's silicating process, though not Zinc powder has been used by which the proposed with this view, tends to the preserva- rosaline compound is reduced to a colourless tion of the cotton, inasmuch as it leads to the leucaniline compound. Dangeville and Gutin deposition of an alkaline carbonate in the have recently substituted a solution of perHe merely adds carbonate of soda. Since the dilute sulphuric acid. material. Mr. Abel's method is still simpler. manganate of potash in a slight excess of This they thicken amount of cotton liable to change is, as we with kaolin, pipe-clay, or gelatinous silica, and The Causes and Prevention of the Spontaneous have said, in the well manufactured article print. Oxidation quickly takes place, and the Decomposition of Gun Cotton-Oxidation by very small, only a little carbonate of soda is fabric is colourless, but for a small proporMeans of Charcoal-Tungsten Steel by Bes- necessary; and with this protection it has tion of oxide of manganese, which is easily semer's Process-New Material for Paper-been determined that gun cotton may be ex- removed by a weak bath of sulphurous acid. A Discharge for Aniline Colours-Failure posed to every condition likely to set up or The lighthouse at Fécamp was last year of a lightning Conductor. promote decomposition without the smallest struck by lightning. As it was furnished risk of change. We may mention here with a conductor, the matter excited great by Mr. Abel surprise, and the cause of the failure of the NOTES ON RECENT SCIENTIFIC DIS- APPLICATIONS. UN COTTON has now taken a permanent G place among our useful explosive agents. another improvement made by the cotton conductor was inquired into. It was found "An Encyclopædia of Architecture, Historical, Theo- in a state of fine division, which with that the rod was carried down into a small retical, and Practical." BY JOSEPH GWILT, F.S.A., other advantages to which we shall allude cistern hollowed out of the chalk and lined F.R.I.B.A. London: Longmans, Green, and Co. 1867. on another occasion, favours the washing with Portland cement. The lesson drawn by F.R.A.S. A new edition revised by Wyatt Papworth, the inquirey is, that it is necessary to place a conductor in contact with a large surface of moist soil. It may be useful to repeat here the conditions necessary for safety. 1. The point or points of the conductor should be sharp; 2. It must communicate with the ground; 3. There must be no break in the length; 4. It must have a proper proportion; and 5. When not carried into a well it must communicate with a large surface of moist soil. Parliamentary Notes. a maximum ratio of expansion, without dispens ing with the peculiar element of economy embodied in the single-acting engine, and in doing so he has had six objects in view. 1st. To reduce the blow impressed on the piston, con. sequent on a high degree of expansion in a single cylinder. 2nd. To increase the power developed on a unit of surface of the piston. 3rd. To isolate as far as practicable the cylinders from the frigirific influence of the condenser. 4th. To reduce the steam space between the two cylinders to a minimum. 5th. To obtain a nearly continuous flow of water with single-acting pumps. And, 6th. To adapt the engine to the requirements of a variable load. In order that a high degree of expansion may be employed, the author proposes to make the total initial in the highpressure cylinder equal to 601b. to the square inch, and to expand the steam rather more than ten times, that the terminal pressure in the lowpressure cylinder may be equal to, or slightly in excess of, the pressure of the vapour in the condenser. far greater percentage of work from a given weight of steam than any other type of engine employed for pumping purposes, when employed under similar conditions. Nor is it always to qualify the necessary statement with the words similar conditions, but it is often does a higher duty when expanding the steam found that a well-constructed Cornish engine nine times than a rotary engine expanding the steam eight or nine times; and, as an obvious consequence, it follows that the peculiar element of economy existing in the single-acting engine is not dependent on the ratio of expansion employed, but in the mode of developing and applying the power. Notwithstanding the advantages which it possesses over its rival, the Cornish engine has not received the amount of attention OUR stock of Parliamentary news is again very of late years which has been bestowed on the meagre, but few matters of scientific interest rotary engine; and in order that the latter having been discussed in either of the Houses engine may produce the maximum economy, since our last. On Thursday evening in the recourse has been had to high expansive work. House of Commons, the proposed grant of ing, to obtain which the crude ideas of Horn£22,800 to inventors of rifled ordnance and pro- blower and Wolf have been developed, a second jectiles, was touched upon. Sir G. Stucley asked cylinder has been applied, and the ratio of exIn the proposed engine, the two cylinders are the Secretary of State for War whether, previous pansion increased with very good results accruplaced each directly over a plunger pump, the to the disposal of any portion of the £22,800 ing. It appears rather strange to the author, plunger being directly attached to the piston-rod proposed to be given to inventors, he was willing that the inferior type of pumping engine should in the usual manner for direct-acting engines. to appoint a committee to inquire into the claims have been selected as the type to receive a of Messrs. Whitworth, Jeffery, Padwick, Lynall higher state of development; and it is this, The streams of water from the two pumps conThomas, Lancaster, and Captain Scott, all of together with the dictates of experience, which verge towards the main pipe, forming the letter whom had devoted much time, labour, and he has had with single-acting engines, which V. An air-vessel is placed on each arm of the money, in the improvement of rifled ordnance induced him to prepare this brief paper for dis-V, with a stop-valve between it and the plunger cussion. The gear of a single-acting engine repump. The nozzles, containing the governor and projectiles, and had hitherto not been rewarded. In the absence of information the supervision than does that of its rival, which is the two cylinders are placed the nozzles containand steam-valves, are placed at the foot of the quires nice adjustment and more intelligent small cylinder at the right-hand side. Between question was a very proper one, but the answer probably one reason why the rotary engine is showed it to be unnecessary. In reply, Sir J. often preferred; it is also easier to apply the ing the steam equilibrium and eduction valves Pakington said he had no intention of proposing latter engine to a variable load. But a massive for the large cylinder. Immediately beneath the the appointment of any such committee. The fly-wheel and sweep-rod appears to the author to latter nozzles is placed the condenser and airWar Department had inquired into these matters, be out of place in a pumping-engine; for it not pump. The system admits of a compact ar and there was nothing for a committee to inquire only requires a large amount of extra space, but rangement, a 95in. and a 60in. cylinder only into. He was not aware that Messrs. Whitworth the moving parts are greater in number; it requiring a building 31ft. 9in. long by 25ft. wide had claimed any reward. Mr. Jefferey had re- requires more frequent repairs; and its period of from out to out. In the proposed design, the Iceived a reward. Mr. Padwick was offered a duration, as a natural consequence, is very much small cylinder is 60in. and the large cylinder shorter. The chief reason for the durable nature of the Cornish engine is the fact that all the working parts are made very massive. It is a great mistake to make an engine light and liable to derangement for the sake of economising a few tons of metal, especially so for water-works purposes, where it is of great importance that repairs should be few, and the engine made last. sum, but he refused it. Mr. Thomas was a bankrupt. Mr. Lancaster received a very hand. some um, and Captain Scott made no claim. From this it would appear that all the parties whose cause Sir G. Stucley espoused are satisfied with their positions in the matter of rewards, although we doubt whether they are in some other respects. The next evening Colonel Sykes asked the Vice-ing. President of the Board of Trade, when the returns relating to the Meteorological Department of the Board of Trade ordered by the House on February 12, last, and the returns relating to memorials on the subject of storm signals, or dered on the 7th ult., would be laid upon the table. Mr. Cave said that he had laid on the table that evening the latter return, and the former would, he thought, be laid on the table early next week. Our agricultural readers will naturally learn with regret, that they will not be able to hold exhibitions of live stock at present, although, for the reasons given, this restriction is doubtless a wise precaution. This decision was made known in the House of Commons on Tuesday, when Mr. Acland asked whether the Privy Council had come to any decision, and if so what decision, on the application of several agricultural societies for permission to hold exhibitions of live stock during the summer of the present year; and secondly, whether such desision, if any, imposed any restrictions on the exhibition of Montague said this subject had been under the serious consideration of the Privy Council for some time. As there were now five places in England which were still infected with the cattle plague, they did not think it would be advisable to alter the Order in Council of March 24, 1866, so as to allow an exhibition of lean, not fat stock, during the present summer. As to the second part of the question, he must remind his hon. friend that the Order in Council of March 24, applied only to cattle, and not to sheep and other animals. animals other than horned cattle. Lord R. SOCIETY OF ENGINEERS. water in the pump is sufficient to enable a ratio nearly 95in. in diameter, which proportion gives length of stroke is the same in both the cases, a relative area of pistons of 1 to 25; and as the the same relative proportion is true for the capacities. The steam is first admitted beneath the small piston, and at the completion of what allowed to escape into the large cylinder beneath is technically called the "in-door" stroke, it is the piston, so that the "in-door" or up stroke of one piston is performed during the "out-door" or down stroke of the other, by which means the two plungers are made to perform the function of a double-acting pump. It is evident that the be 2.5 times that on the large, since.1 to 25 is mean effective pressure on the small piston must the relative areas of the two cylinders. The two plungers being of the same diameter, the author proposes 9.91b. as the mean pressure in the large cylinder. This having been decided, it is at once evident what must be the initial pressure. Steam expanded 2.5 times, with a mean pressure of 99, must have an initial pressure of 13lb. It is also evident that the mean effective pressure in the small cylinder must be 99X25; but since the small piston, during its down stroke, is subject to a mean back pressure of 99, it follows that the total mean pressure must be 99X3'5, which is equal to 34-61b.; for the author proposes not to employ an equilibrium valve for the small cylinder, for reasons which will soon become apparent. The author regards it as an axiom that the single-acting engine possesses a peculiar element of economy; and he would now make a few sug. gestions towards a higher development of the type, and a peculiar adaptation to waterworks purposes. Of the two types of single-acting engines, the beam engine is considered by the majority of engineers, probably, as superior to the direct-acting engine; and it certainly is, inasmuch as, by the employment of a massive beam, the inertia of the extra amount of matter to be put in motion enables a higher degree of expansion to be employed, and also renders the motion of the piston more uniform. But the direct acting type possesses certain other advantages, and when employed to pump against a great head of water, with a single-acting pump, the weight of matter required to displace the of expansion of from four to five to be employed. much sweeter than a double-acting engine of the A well constructed Cornish engine will work same power. There are no bearings in the The initial pressure may be anything in the former engine to be repeatedly thumping; the small cylinder above 346lb., and the point of moving parts are rigid, and as long as the catch-cut-off must be such as to give that as the mean pieces are kept from contact with the spring pressure. The author proposes to employ much beams, the motion of the piston is free from vibrations at a mean speed of 300 ft. per minute, or a maximum speed of 600ft. The author is acquainted with many direct-acting engines, with 10ft. stroke, making 15 strokes per minute in regular work. The great advantage attending this class of engine is, that it possesses but few moving parts to keep in repair, and is very far less expensive than the beam engine; also requiring small and, therefore, less expensive buildings. It has occurred to the author, that if the direct-acting type of engine can be employed with a ratio of expansion of nine or ten, and an initial pressure of 60lb. to the square inch, without risk of injury to the machinery, higher pressures than is usual for single-acting April 1st, 1867, W. H. Le Pouvy,, Bay, grey very economical results would follow, such a slightly increased the power developed on each sident in the chair, the following paper on pumping engines for town water supply by Mr. Henry Davey was read:-It is an admitted fact, with the majority of engineers, that the Cornish or single-acting engine is capable of developing a result cannot be obtained with a single cylinder. unit of the area. It is usual to put a total load of from 14 to 15lb. on the square inch of the pistons of Cornish engines; but it must be remembered that the ratio of expansion is more than double in the proposed engine than is usually employed. |