a2, fig. 8, represents a rotating tumbler, arranged in a recess in the cam wheel D, provided with journals and star wheels on each end, and with a spiral groove a3 in the periphery of the portion between the journals, which traverses from one end of the enlarged portion of the tumbler to the other, and back again to the place of starting at one revolution of the same around the said tumbler. Recesses a4 are also provided in the tumbler on each side at the angles where the groove changes its direction, which recesses communicate with the groove. The movable end of the helical vane is provided with a projection a5 which takes into the said groove, passing through a slot in the face of the cam wheel D, communicating with the recess wherein the tumbler is arranged. The said projection springs into the recesses a4 in the tumbler, after each change of the vane has been effected, which will be presently described, and rests therein during the movement of the comb bar from point to point where the changes are effected. The star wheels on the tumbler are provided with four teeth or tappets. a6 represents dogs which are attached to the rack bar so as to slide thereon, and may be secured at any desired point by the swinging levers a7, which drop into the notches between the teeth of the rack bar. The said dogs are provided with studs 48. The swinging levers a7 are bent from each side toward the tumbler, and serve as gauges for setting the dogs. When the comb bar has been moved in either direction, so as to bring one of the dogs a6 nearly into contact with the cam wheel D in the revolution of the latter, a tappet on the star wheel on the side next to the dog will strike the pin a8 on the said dog, and the tumbler will thereby be turned a quarter of a revolution, which will move the vane on the periphery of the cam wheel, from a helical to an annular position, whereby the movement of the comb bar in either direction will cease, while the motion of the other parts of the machine will continue. As the cam wheel D, however, makes another revolution, another tappet on the star wheel will be brought into contact with the pin a8 on the dog, and the star wheel again moved a quarter of a revolution, whereby the vane will be again moved into a helical line, but in the direction opposite to that it occupied previous to the movement of the tumbler, whereby the comb bar will be again set in motion, also in the opposite direction, which will continue until the dog a6 on the other side of the cam wheel comes up and effects a similar change of the vane. As the vane is central, or in the same plane, for the greater portion of the circumference thereof, the motion of the comb bar is intermittent. By reason of the continuance of the comb bar in its position during two revolutions of the cam wheel at the point where its direction of motion changes, as above explained, two stitches are made on one finger at the outer edges of the fabric, thereby giving to the edges their full complement, which would not otherwise be the case; F represents the needle arm, and G represents the looper arm, both of which are pivoted to the bracket B and actuated by cam grooves in the side of the cam wheel D. The arm F is provided with a stud b which projects into the groove b1 of the cam wheel, whereby a swinging motion is communicated to the said arm. The lower end of the said arm is provided with a slot and a spring, which latter is provided with a stud 64 and a hook 65. The stud b4 projects through a hole in the needle arm F. The toe 66 of the needle arm and the heel b7 are angularly shaped as shown in the engravings, for the purpose of locking tightly with the needle carriage H, which is provided with a notched recess to correspond with the foot of the needle arm. The needle carriage is provided at its lower edge with a semicircular recess, and fits into the groove b2 in the bottom of the foot of the needle arm, and the spring hook 65 catches under it in the groove, whereby the needle carriage is easily attached or detached from the carrier, and is also firmly connected to it; I represents a yarn tension wheel, supported on a pin secured to the needle carriage; 68 represents the needle and 69 the knocking-off bar; K represents the twisted looper shaft, to which the looper head cl is adjustably connected, being provided with a socket, into which the end of the shaft K fits, and is held therein by a set screw. The looper shaft is arranged on its bearings so as to slide lengthwise therein, and is moved in either direction by the forked arm G at the same time that it communicates rotary motion to the said shaft. The outer end of the shaft is provided with a pin, which, coming in contact with the circular cam c3 governs the forward movement of the looper toward the comb teeth, in respect not only to the said forward movement but also in respect to the position of the looper in its rotary movement at the time of the said forward movement. The operation of the machine is as follows:The fabric being suspended from the fingers of the comb, as represented in fig. 3, the needle is caused to move forward, together with the knocking-off bar, at the proper time by the cam D driving the point through the loop on the finger, and afterwards knocking it off, as shown in fig. 4 on to the needle. At this moment the looper is moved forward and also commences a rotary motion, engaging its point in the loop of yarn which hangs under the needle between the eye of the same and the connection of the yarn with the old loop, as shown in fig. 5, which it takes up, and carries with it in its rotary movement, until it arrives at the position shown in fig. 6, at which time its rotary motion ceases, but it moves forward following the needle, which now begins to recede, until the position shown in fig. 7 is assumed, at which time the looper ceases its forward movement, while the needle continues its backward movement, withdrawing from the loop and tightening up the yarn, so that its tension holds the newly formed loop on the finger, while the looper recedes to its first position, leaving all the parts as indicated in fig. 1. The alarm apparatus shown in figs 13, 14, and 15 may be thus explained:-A in such figures is a bell mounted on a spindle B, from which there extends an arm C. Extending through the said arm and pivoted therein is a short shaft D. A fork E projects from one end of the shaft. Furthermore, a hammer F is extended from the other end of the shaft and into the bell. A helical spring G hitched upon a stud H projecting from the shaft and also hitched upon a hook I projecting from the arm near the bell spindle serves to throw the hammer against the bell, when the fork brings up against a stop K projecting from the arm, the whole being arranged as represented. A thread guide L may also be extended from the arm, and with respect to the fork, as shown in the said figs. 13 and 14. This alarm apparatus is to be applied to the knitting machine at some proper place between the spool and the needle thereof, the thread from the spool being run between the next adjacent prongs of the fork, or, in other words, first through the eye of the guide and next through the fork, there being narrow slits or spaces between its prongs. In case there may be a knot in the thread such knot on being drawn in contact with the fork will cause such and the bell hammer to decline until the knot may slip out from between the prongs. Immediately on such taking place the fork will be set free, and the spring will throw it back to place against the shoulder or stop, and also throw the hammer up against the bell, and thereby sound an alarm. will have to join the depot battalion in case of war THE ORGANISATION OF THE PRUSSIAN point of concentration; and they travel in pursu ARMY. 7. MOBILISATION. PRINTED instruction, issued from the War A Department, and called "Plan of Mobilisation, Mobilmachungs Plan), is in the hands of all officers concerned in the business exclusively. As the regulations contained therein would give the enemy valuable information the book is not permitted to appear for public sale. Any changes resolved upon are carefully inserted, and the whole contents often altogether revised. This instruction, in the first place, contains the standing orders, prescribing what is to be done each day, counting from the date of issue of the order of mobilisation as the first, and runs about in this manner: ance of a timetable fixed long before for a given In a case of surprise it would be possible to let Be it remarked on this occasion that evory officer and soldier actually in the field receives, under all circumstances, more pay than any one who is not yet in active service. The Landwehr is not always in all provinces and at once called out. Of course, on July 1, 1870, First day-Issue of order of mobilisation. Se- all the Landwehr in the western provinces were cond day-Receipt of order (at all stations; de- called out, the fortresses on that frontier needing spatch of orders for reserves to report at head their full garrisons at once. Likewise the Landquarters of Landwehr battalion on the fifth day- wehr of the provinces near the German Ocean and for the Landwehr on a specified later day; departure the Baltic were ordered out at once, but the rest of all details for cavalry and artillery horses; were called out later, when wanted for securing despatch of orders for calling in horses of county the communications of the advancing field army. (circle). Third day-horses of circle arrive at Landwehr artillery and engineers get plenty of Landwehr battalion headquarters. Fourth day-employment in fortresses and at sieges. meeting of board for appraising and assigning It is obvious that by anticipating the recruits horses; arrival of details of cavalry in East for one year, by taking them at nineteen years of Prussia and other provinces for receiving age for filling up the depot battalions, and by horses. Fifth day starting of horses for falling back upon men between thirty-five and different garrisons; arrival of reserves at forty for the Landwehr, the reinforcements could Landwehr battalion headquarters. Sixth be increased to a great extent; but these measures day-horses from Landwehr battalion reach would only be resorted to in case of a very disastroops; departure of reserves from Landwehr trous campaign. battalion headquarters for different garrisons. Seventh day-arrival of horses from further provinces; reserves arrive at their battalion garrisons. Eighth day—equipment of reserves and formation of depot battalions: arrival of Landwehr at Landwehr battalion headquarters. Ninth daystarting of field army for post of concentration or embarkation by rail. Tenth day-arrival of re-de-camp. cruits at Landwehr battalion headquarters. Eleventh day-examination and assignment. Twelfth day-departure to join depot battalion, &c. We are, of course, unable to vouch for the correctness of these dates, which are merely given as an illustration. The field battalion of infantry, corresponding to the Landwehr battalion, being 400 men in peace, receives from the latter the next six years' reserves (133 per year), say 800 men. Of these 600 increase the field battalion to its proper number of 1,000; the remaining 200 form with the 400 of the two other battalions of the regiment the depot battalion of the regiment, which, after a few days, is increased to 1,200 by the arrival of 400 recruits. These are the men due on October 1 next called in at once. The selections for the depot battalion are made in the following manner: -In the first place, all men are taken who are temporarily sick or unfit for field servico; next, men who happen to have just now urgent applications for exemption pending which it has not yet been possible to decide upon; and ultimately the oldest men. This battalion gets organised in six companies, 200 each; and besides the drilling of recruits it has to do garrison duty in such fortress as it has been designated for. The officers are assigned every year according to roster-that is to say, on October 1 the officers are assigned who It may be permitted now to give the "Ordre de Bataille" of a Prussian army corps, and the number of depot and Landwehr troops pertaining to it : General commanding, general. Chief of staff, colonel of general staff. Captain of general staff; captain of infantry, general staff; one captain and one lieutenant of infantry, aides; intendant of division; judgeadvocate. Third brigade, major-general-aide-de-camp, first lieutenant of infantry; fifth regiment of infantry; battalion sharpshooters. Fourth brigade, major-general-aide-de-camp, first lieutenant of infantry; seventh regiment of infantry; eighth regiment of infantry. Artillery, major-battery 4lb. pieces; battery 8lb. pieces. Regiment of cavalry. Cavalry division, lieutenant-general-major of general staff; one captain and one lieutenant of cavalry, aides; intendant of division; judge-advocate. First brigade, major-general-first lieutenant of cavalry, aide-de-camp; three regiments of cavalry. Second brigade, major-general-first lieutenant of cavalry, aide-de-camp; three regiments of cavalry. Artillery, major-two batteries horse artillery. Reserve artillery-colonel commanding field artillery regiment, commanding; two lieutenants of artillery, aides (in regard to all administrative objects considered as the fourth division of corps); intendant of division; judge-advocate; four batteries 4lb. pieces; four batteries 81b. pieces; four batteries horse artillery; engineer battalion; pontoon train; ammunition train. Commandant of headquarters, captain or lieu-one additional battalion sharpshooters, and several tenant of cavalry. Staff guard detachment of infantry and cavalry. Adjutant, lieutenant of artillery. other corps, I think, have no fusileer regiment; but the numbers adduced are near enough to arrive at a rather correct total: Field army in 13 army corps, 456,560; depot troops, 167,310; Landwehr, 332,800: total, 956,670, or 377 battalions, 416 squadrons, 1,248 field pieces. The field army is at present altogether in France, and certainly in this strength, as the Intendant of corps with several officers of his depot battalions must have completed their ranks corps. Judge-advocate of corps. First division, lieutenant-general-major of general staff; one captain and one lieutenant of infantry, aides; intendant of division; judge-advocate. First brigade, major-general-aide-de-camp, Second brigade, major-general-aide-de-camp, by November 1. How many divisions of Landwehr have crossed the frontier cannot be ascertained at present. Brigades and divisions of Landwehr are formed when they start. In regard to the field army, it ought to be remarked that the mobilisation is merely an expansion; the bodies of troops, commanders, &c., remain the same as in peace. As few changes as possible is the rule. That the armies of South Germany are not included in this count need not be mentioned. Bavaria has furnished two field and one reserve corps; Wurtemberg and Baden have furnished one small corps of about 20,000 each. Their organisation is not yet quite carried out on the Regiment of cavalry. Prussian system, though the main points of the Second division, lieutenant-general-major of system have been adopted since 1866. 8. CLOSING REMARKS ABOUT THE SYSTEM. The Prussian or North German army cannot, in the usual sense of the word, be called a "standing army." It is a great national military training school, in which the teachers alone-a part of the officers and non-commissioned officers-are permanent. The organisation combines a system of militia with the strictness of training which makes the militia in fact an army. The Prussian army is not by any means an instrument for the use of a monarch who should be inclined to undertake wars for the purpose of gratifying personal ambition or lust of conquest. It is not an instrument, either, to support tyranny and usurpation of constitutional rights. How could an army of 200,000 men compel the 250,000 reserves to put in an appearance if they would not? Single or local cases of disobedience could be disposed of and punished, but a general disposition to disobey would have a natural momentum not to be overcome. It is undeniable that this system of national defence is rather exacting and burdensome to the nation; but, strange to see, the Prussian nation has, in spite of it, kept well up with the progress of her neighbours in industry, commerce, husbandry, and science. The expenses are great, but the finances of Prussia are in a better condition than those of any other European nation. The amount of money spent for the national defence, compared with the total revenues, is smaller in proportion than in the budget of France, Austria, or Russia, and the amount of taxes paid per head is smaller than in most other European States. Neither have other important institutions been neglected on account of the army; especially public education has not suffered. It must even be admitted that the system can hardly be maintained except by a nation in which education is so general as in Prussia. That Prussia's neighbours will try to imitate her system closely seems probable, but the backwardness of general education will be a stumbling-block to several of them in an attempt to do so. Political economists complain that the productive labour of 200,000 men every year is lost in Prussia-that the increase of public wealth could be so much greater. It might be possible to teach a man the technical business of a soldier in three months; but discipline, habits of obedience, of frugality, of endurance, cannot be taught in that time. And then, in times when the political aspect in Europe seems to permit it, a reduction of the term of service could take place, and the efforts of the Prussian officers would manage to maintain the present standard of efficiency with two years' service. This has taken place before now. During the years of peace after 1815, when exhausted Europe was recovering from the devastation brought about by Napoleon I., a period without any wars between any of the great powers, the term of service in Prussia was reduced to two, even to one and a-half years; and this will certainly be done again as soon as the position acquired by Germany now will permit her to do it with something like safety. Finally, the Prussian nation does not consider the accumulation of wealth as the first and only purpose of life. To be able to defend home and property is considered at least just as desirable as to make money, and a hard experience has taught the German nation how desirable it is. If you have neighbours around you who may want what you have, and who are always ready to ask, you must be prepared to hold your own. It is not even the ambition of rulers alone which threatens war; nations may do wrong just as well as rulers. It was not King George alone who wronged the American colonies; it was the English Parliament, backed by a majority of the nation, which refused redress. It was not Napoleon alone who made the present war; the majority of the French nation applauded his action. A general republic in Europe, of which some people dream nowadays, would not prevent war in Europe. We have seen even here how troublesome it was to beat reason into the heads of a considerable minority of one nation. Armies for executing the will of the majority would have to be called out in republican Europe as often as nations go to war now. The necessity of being prepared is obvious in Europe, and to be well prepared is cheaper in the long Any parallel between Europe and the United States is out of place. We are in the happy condition of having no neighbour on our continent which is our peer in power. Nobody could attack us with any reasonable chance of success, much less surprise us; a position which to a certain though much smaller degree is run. enjoyed by England too, on account of her insular situation. But the continental nations are not so fortunate; they must live beside each other, and war will come unless human nature be changed altogether. The Prussian nation has had a historical mission, to unite and reorganise Germany-a mission now on the verge of fulfilment. The system of national defence, commonly called the Prussian Army, has been the main instrument to achieve the present unity of Germany, and it will be by means of this system that Germany will maintain it. Most probably Germany's present position will produce in Europe more of a tendency towards peace than towards war. Prussia is indebted to her kings for the introduction, preservation, and improvement of this system; and the loyalty of the nation towards the house of Hohenzollern, much greater, by the bye, than it is here usually admitted to be, is well deserved. DREDGING AND EXCAVATING MACHINE AT CHATHAM DOCKYARD. Tsimple arrangement of machinery which has HE accompanying engraving illustrates a been adopted by the Lords of the Admiralty for use in her Majesty's Dockyard at Chatham. Its use is for making excavations under water in the construction of sea walls or harbour works, and for removing accumulations from docks, harbours, and rivers. Besides these purposes it is available for raising sunken ships, or removing water, earth, sand, and gravel from foundations, cylinders, caissons, and similar structures. In our engraving A is a casing containing a revolving disc, which is faced with steel and has a steel screw B, affixed to the end of the revolving shaft. This screw loosens, stirs up, and agitates the materials, as shown by the bank of mud or earth C. A vertical discharge pipe E, up which the loosened material is carried, is stayed by the chains D. The head A is raised and lowered by ropes worked from the deck K laid on the pontoons I I, and on which the engine and boiler are placed. F is a continuation of the discharge pipe E, and which delivers the materials and water discharged by the excavator into barges. G is the vertical shaft of the revolving wheel, which slides through the driving pulley, the latter being secured by a sunken key to the shaft. H is a portable engine for driving the apparatus. This machine can be so modified that it can be used for separating and elevating small coals, ores, gravel, lime, grain, seed, and other similar substances, and at the same time it can be used for washing or freeing the substances from earthy or other impurities. To enable the machine to be readily raised or lowered, or the length of the vertical discharge pipe to be increased or diminished, a telescopic or sliding pipe is inserted in its length, regulated by chains from the top, thus affording facility for lowering the apparatus to and working it at any desired depth below the surface. This machine is the invention of Messrs. Gwynne and Co., of the Essex Works, Strand, and was selected to be sent to Bermuda for excavating the bed for the new floating dock there. N ROYAL ALBERT HALL. On Wednesday last there was an inspection, by invitation of the Exhibition Commissioners, of the new Hall at Kensington, the gentlemen invited being chiefly architects, engineers, builders, and other interested in the constructive arts. These gentlemen were invited for two purposesto inspect the hall, and more especially the gallery in which architectural drawings and models are to be displayed at the ensuing Exhibition; and to receive illustration of the acoustic properties of the building. The work connected with the two tiers of boxes, the balcony, and the picture gallery, is proceeding rapidly, as also the completion of the roof. Is the displayed by drawings and models, excited much admiration; the space was considered abundant, and the light from the roof ample yet without glare. The picture gallery, in which archi The acoustic experiments were similar to those made on the occasion of the Queen's recent visit to the Hall, and were even more successful, from the circumstance that a considerable portion of the scaffolding has been removed since then. Miss Williams and Master F. Britten, the son of ore of the workmen employed on the building, again assisted," and there were in addition pianoforte, violin, and flute. The effect that an audience may have upon the waves of sound cannot be predicted with certainty, but the experiments hitherto made on Wednesday aud previously have been so completely successful as to leave no room to doubt that, as regards acoustical properties, the Hall will be all that can be desired. This is of course a matter of great importance if the Hall is to become, as is intended, the headquarters of our national training school for music. We noticed from the visitors' books placed at the entrances that about 140 gentlemen, including many eminent architects, engineers, builders, and scientific men, were present. Although great activity is being displayed in the prosecution of the work, there is still so much remaining to be done as to give cause for anxiety that the margin of time between now and the 1st of May will barely suffice for the completion of the work. ILLINOIS AND ST. LOUIS BRIDGE. (Continued from page 443.) The fact that the air lock tenders were in no pressure may be admitted into the air lock so rapidly gentlemen maintained that a slower transition from that this natural remedy will not in all cases relieve the abnormal to the natural pressure would have it. By closing the nostrils between the thumb and been less injurious; others claimed, on the contrary, HE filling of the air chamber was executed in the fingers, shutting the lips tightly and inflating the that it was from the too rapid application of pressure THE of checks, the Eustachian tubes are opened and the in passing from the natural into of pressed immediate direction of the superintendent of con- pressure on the inner and outer surfaces of the tym-air. struction. The preparation and disposition of the panum is equalised and the pain prevented. This case affected, although subjected many times during concrete were made in the air chamber (from 103ft. method must be used and repeated from time to time a watch of two hours in the air lock to rapidly alto 1104ft. beneath the surface of the river). as the pressure is let on, if it be increased rapidly. ternating conditions of the atmosphere, at one The filling of the air chamber with concrete com- No inconvenience is felt by the reaction when the moment in its normal state in the lock, and five menced on March 2 last and was finished on May 27 pressure is let off, as the compressed air within the minutes later exerting a pressure of 50lb. per square last, the working time being 53 days. The space drums has a tendency to open the tubes and thus inch upon every part of the body, would seem to filled may be fairly stated at nearly 36,000 cubic feet. facilitates its escape through them, whereas increas- prove both of these theories unsound, and lead us to The area of the base of the pier is 4,020 square feet, ing the pressure has the effect of collapsing them, believe that in the length of time to which the and the height of the chamber 9ft. The caisson and therefore makes it more difficult to admit the human system is subjected to this extraordinary was stopped as soon as it touched the bed rock. compressed air within the cavities of the ears. It pressure exists the real source of danger, and not This was at its south-west corner; at the north-frequently occurs, however, from some abnormal from any rapid alternations of pressure to which it west corner its edge was 8in. from the rock, the condition of these tubes, as when inflamed by a cold is exposed. After the caisson reached the rock I north-east corner was 16in., and the south-east in the head, that neither of these remedies will re- have frequently, when passing through the air lock, corner 8in. It will be seen from this that the rock lieve the pain. To continue the admission of com- admitted the compressed air into it so quickly that was, fortunately, very nearly level. The sand be- pressed air into the lock under such circumstances neath the edge of the caisson was removed, the rock would intensify the suffering, and possibly rupture laid bare, and the space filled carefully with eonthe tympanum, therefore the lock tenders were crete, the air pressure being sufficient to prevent a particularly instructed to shut off the compressed at more rapid infiltration of the water under the edge about the ears; and then, if it could not be relieved the moment any one in the lock experienced pain of the caisson than could be managed by the pump; by the above means, the lock was opened and the ing arrangements within it. The sand seemed packed so firmly that no trouble was taken to person was not permitted to go through into the air barricade it out of this space between the rock and chamber. Sometimes fifteen minutes were occupied the edge of the caisson. When the entire edge of in passing persons through the first time, after the caisson and the space under its two great girders which they usually had no further trouble from this cause. none but those well accustomed to it could relieve the pressure upon their ears, and yet I felt no ill effects whatever from this rapidly increased pressure; and in going out I have let the pressure off 32deg. Fah. in consequence. These transitions ocso fast that the temperature in the lock has fallen cupied but three or four minutes. The fact that the air chamber was briefly visited by thousands of persons, including many delicate ladies, even after it had reached the bed rock-some remaining as long as an hour in it without any of were thus concreted the rock in its interior was them experiencing the slightest ill effects from the gradually cleared of sand and the concrete placed The fact that the depth penetrated by the air pressure-and the fact that no cases of any importdirectly upon it in layers of 9in. or 10in. in thick-chamber was considerably greater than that hitherto ance whatever occurred among the workmen after ness, the closing courses under the roof of the reached in any similar work left me without any the watches were reduced to one hour, satisfies me chamber being stoutly rammed in place. The air benefit from the experience of others in either that this is the true cause of the paralysis, and that locks were then filled with the same material and guarding against any injurious effects of this great by lessening still more the duration of the watches finally the shafts. The concrete was made of broken pressure upon the workmen and engineers subjected a depth considerably greater can be reached without limestone thoroughly washed, the interstices being to it, or of availing myself of any known specific for re-injury to the workmen. Too long a continuance in filled with mortar made of equal parts of Akron lieving those affected by it. When a depth of 60ft. had the air chamber was almost invariably followed by been attained some few of the workmen were affected symptoms of exhaustion and paralysis. was rarely accompanied by pain, and usually passed shaft, but generally after the stairs were ascended, by a muscular paralysis of the lower limbs. This Symptoms of paralysis rarely occurred in the off in the course of a day or two. As the penetration and never in the air lock or air chamber. of the pier progressed the paralysis became more (To be continued.) difficult to subdue. In some cases the arms were involved, and in a few cases the ephyncter muscles and cement and pure sand. During the sinking of the pier the sand pumps designed by me for this special purpose gave great satisfaction and proved entirely successful. One pump of 34in. bore was found quite capable of raising 20 cubic yards of sand 120ft. high per hour; the water pressure required to supply the jet being about 150lb. per square inch. bowels. An The patients also suffered much pain in the joints when the symptoms were severe. average of at least nine out of ten of those affected suffered no pain whatever but soon recovered, and generally returned to the work. The duration of the watches in the air chamber was gradually shortened from four hours to three, and then to two, and fiually to one hour. The use of galvanic bands or armour seemed in the opinion of the superintendent of construction, the foremen of the chamber, and the men, to give remarkable immunity from these attacks. They were all ultimately provided with them. These bands were made of alternate scales of zinc and silver, and were worn around the wrists, arms, ankles, and waist, and also under the soles of the feet. Sufficient moisture and acidity were supplied by the perspiration to establish galvanic action in the armour, and as the opinion among those most accustomed to the chamber was almost unanimous in favour of this remedy I am very much inclined to believe it valuable. NEW CHURCH CLOCK. HE new clock has just been fixed in the tower of the ancient parish church of St. Mary, Minster, Kent,to replace the old one, which was originally made 256 years ago, and having been repaired from time to time it wore itself out at last, and ultimately became so erratic in its movements that it was determined by the inhabitants to have a new one. A committee (assisted by the vicar and churchwardens) was therefore formed for the purpose of raising the necessary funds for its purchase, and their efforts proving successful a meeting was subsequently held in the vestry, the Rev. A. H. Sitwell, vicar, in the chair, when it was decided that the work should be placed in the hands of Messrs. Gillett and Bland, of the steam clock factory, Croydon, who are a firm highly distinguished for the ability they have shown as church clock makers, and since the erection of so large a public clock is a rare occurrence in this part of the country we will give a brief description of it, feeling sure that it will prove interesting to our readers. The clock is fixed in the chamber of the tower below the bells, and rests upon strong beams, the ends of which are let into the side walls. It strikes the hours upon the tenor bell, weighing 22cwt. (with a hammer of 501b. weight), which can be heard for many miles round, and chimes the four quarters on four bells (similar to those at St. Mary's, Cambridge), weighing 464cwt. The time is shown upon the old dial, which is about 7ft. in diameter, and has been thoroughly repaired, painted, and gilt. The pressure of air in the air chamber was very accurately determined by the depth of the caisson below the surface. Any greater pressure than that due to the depth caused the air to escape beneath it, but when the caisson had penetrated into the sand to a considerable distance it was discovered that the water level formed by the air under or across the bottom of the chamber was nearly a foot lower than the bottom edge of the caisson. When the caisson was but a few feet in the sand the air forced its way up by its sides in one or two currents of large volume, but as it penetrated more deeply the passage of the air through the sand evidently became more difficult, and it appeared in small bubbles 60ft. or 70ft. distant from the caisson. This retardation of the escapement of the air from beneath the caisson caused an increase of air pressure by which the water was held at a greater or lesser depth below the line of the bottom of the air chamber. The sand inclosed in the air chamber and forming its floor was usually 1ft. or 2ft. more elevated than the lower edge of the chamber, and was entirely devoid of water, Immediately on the manifestation of greater sevethe air pressure expelling the water from it down rity in the symptoms a hospital boat was fitted up below the edge of the caisson, as just stated. The at the pier, and one of the ablest physicians in the distance to which it was thus expelled and main- city was engaged to attend those affected, and also tained was at no time discovered to exceed 10in., and to institute such sanitary measures as his judgment generally it was not over 8in. This would give an should dictate. A careful examination of the health air pressure equal to nearly 1ft. more than the and bodily condition of every workman was daily depth of the caisson, or about 1-3lb. per square made, and none were permitted to engage in the work This difficulty of the escapement without the approval of the doctor. These most of the air through the sand was increased severely affected were sent to the city hospital, and somewhat by concreting under the edge of the had the benefit of the advice and treatment of its caisson on the rock, and the actual air pres-resident physician. The total number of men em- The going part of the clock has to be wound once sure could then be no longer accurately determined ployed in the air chamber of this pier was 352; of in eight days and the striking and quarters twice a by the height of the water above. The pressure this number about 30 were seriously affected. Not-week, which is found to be preferable to those that gauges usually indicated a pressure of 1lb. or 21b. withstanding the care and skill with which those go eight days, because much less weight is required more than the depth of water would give by calcu- most severely attacked were treated 12 of the cases to lift the heavy hammers, and therefore saves conlation. This was caused in a great measure, how-proved fatal. Each one of these, without exception siderable friction and strain upon the clock. The ever, by the friction of the air in the pipes, I believe, was made the subject of careful inquest by clock is made on the horizontal plan, and the frame the gauges being at the pumps and not in the air the coroner, aided by an autopsy conducted usually by is an elegant design, very strong and firm, of solid chamber. A column of water 110ft. 6in. in height some of our most skilful surgeons and physicians. cast iron, screwed together with wrought-iron nuts would be equal to a pressure of 47.961b. per square Whilst the exciting cause in all of these cases was and bolts, so constructed and the wheels so disposed inch, assuming the weight of the water to be 62.5lb. doubtless the exposure of the system to the pressure that any wheel can be separately lifted out of the per cubic foot. The greatest pressure marked by of the condensed air chamber the habits and condi- frame without either taking it to pieces or removing the gauges was 521b., and it is not probable that the tion of several of those who died were, at the time any of the other wheels. It is 4ft. 6in. long, 2ft. 6in. pressure in the air chamber ever exceeded 50lb. or they went to work, such as would have excluded in height, and 2ft. 6in. wide, and the clock altothem from it if subjected to the examination of Dr. gether is 6ft. 6in. long, 3ft. wide, and 3ft. in height. Jaminet, and the verdict in about one-half of the The escapement, which is the most important part cases gave a totally different cause for the death of of the clock, is a very ingenious mechanical contriv the patient. Nearly or quite all of these deaths hap-ance, and has been made with great skill and judgpened to men unaccustomed to the work, several of ment. It is quite different in construction to those them to men who had worked but one watch of two generally applied, and is technically called a hours. In contrast to this is the fact that quite a large number of the men (certainly one-half of those constantly employed) commenced with the work at its inception and remained throughout its continuance entirely without injury or inconvenience. inch more. 51lb. The first symptom manifesting itself, caused by the pressure of the air, is painfulness in one or both ears. The Eustachian tubes extending from the back of the mouth to the bony cavities over which the drums of the ears are distended, are so minute as not to allow the compressed air to pass rapidly through them to these cavities, and when the pressure is increased rapidly the external pressure on the drums causes pain. These tubes constitute a provision of nature to relieve the ears of such barometric changes as occur in the atmosphere in which we live. The act of swallowing facilities the passage of the air Much diversity of opinion was expressed by the through them, and thus equalises the pressure on medical gentlemen who investigated the symptoms both sides of the drums and prevents the pain. The and held autopsies of the deceased. Some of these "gravity escapement," the invention of E. B. Denison, Esq., Q.C., who was the designer of the clock at the Houses of Parliament. We are informed that it is so superior to all others that no large clock made in the ordinary way can be made to keep anything like such accurate time as those made with this escapement. The pendulum is 6ft. long, and vibrates once in 14sec., and has a cylindrical ball of cast iron at the bottom weighing about lcwt. The motive power is given to the clock by weights suspended from each of the three iron barrels by patent iron wire lines, and carried over pulleys from the top of the clock chamber weighing over half a ton and requiring considerable strength to wind them up; an apparatus (similar to a crane) has been applied, by which means they can be wound up with comparative ease, but it takes more time than when the winding is performed in the ordinary way. The main wheels are 14in. in diameter, and all the rest of the wheels are of hard brass, beautifully turned, cut, and polished by steam machinery. There is an engraved and silvered dial on the clock for the purpose of adjusting and regulating the outer hands. The whole machinery of the clock weighs altogether over one ton. The bells are very ancient, more particularly the fourth, which was most probably cast before the Reformation. The following is a description of them :— Diameter Weight. No.Note. at mouth. cwt. qrs. lbs. 1. B 2ft. 10in. 8 2 0 2. A 3. G 3ft. lin. 10 0 0 12 0 0 4. F sharp ft. 5ģin. 16 0 0 5. E 3ft. 11 in. 22 0 0 68 2 0 Inscription. "Josephus Hatch, made in 1636.” "Josephus Hatch, C.W." There are many other improvements in this clock deserving of notice, which would require more space than we can afford here to fully explain: enough it is to say that great skill has evidently been displayed, not only in the execution but also in the construction. It is a sound, substantial piece of work, strong and able to go through its business without complaining, and we doubt not but that it is the finest specimen of large clockwork in this part of the country, of which the inhabitants of Minster have every reason to be justly proud, for even the Canterbury Cathedral clock (which should be the best in the country at any rate) only strikes the "ding dong" quarters on two bells.Kentish Gazette.' PRIVATE BILLS OF THE SESSION. Tprescribe that copies of the private bills to be THE gas tubes, 40 to 425. Copper: smelters are refusing to sell except at the advance. English tough ingot, £69 to £70. Chili slab, £64 to £65. Tin: remains firm. English ingot, £129 to £130. Straits, £129 to £130. Lead: selling freely; best English soft pig, £19. Spelter: unchanged; English, £17 15s. to £18; Silesian, special brands, £17 15s. to £18. and fills his chest with water, so that he becomes, to 51s. for No. 1. Welsh bars, £6 10s. to £6 WEEKLY CHEMICAL, MINERAL, AND (From J. Berger Spence & Co.'s Manchester Circular, THE chemical trade has been quiet during the is firm. All literary communications should be addressed to the Editor of the MECHANICS' MAGAZINE. Letters relating to the advertising and publishing departments should be addressed to the publisher, Mr. R. Smiles, MECHANICS MAGA ZINE Office, 166, Fleet-street, London. To insure insertion in the following number, advertisements should reach the office not later than 5 o'clock on Thursday evening. We must absolutely decline attending to any communications unaccompanied by the name and address of the writer, not necessarily for insertion, but as a proof of good faith.-ED. M. M. Advertisements are inserted in the MECHANICS' MAGA ZINE, at the rate of 6d. per line, or 5d. per line for 13 insertions, or 4d. per line for 26 insertions. Each line consists of about 10 words. Woodcuts are charged at the same rate as type. Special arrangements made for large advertise ments. RECEIVED-J. T. W.-J. L. S.-T. B. H.-M. L. S. S. W. H.-B. T. F.-J. T. W.-S. W. P.-W W. A.- Teetings for the Meek. TUES.-Royal Institution-Pyofessor Odling on "Burning and Unburning," at 3 p.m. (juvenile lectures.) and Unburning," at 3 p.m. (juvenile lectures.) Fabal, Military, and Gunnery Items. about 18 vessels of surviving the Tu are in IRON shipbuilding on Thames; the course of construction. THE "Globe" learns that the 66 Vanguard," which has just returned from her experimental sea trip, is to have her water ballast taken out at Devonport, to be replaced with fixed iron ballast and cement, and will probably have some alterations made in her steering gear. THE "Irish Times" announces that the order for enrolling and enlisting the Irish militia has been issued from the War Office. The training will take place in the spring, and in the meantime the various regiments will be immediately recruited up to their proper strength, and, where the circumstances will admit, that strength will be increased. new army of that nation. Every maker of tin goods in the kingdom other than the merest tinker is now occupied in this work. The purchasers will take as many articles as can be manufactured. The greater number of articles produced the greater the satisfaction of the department. Nor do they now haggle as to price. tracts have been concluded during the week. In fairly maintained, and transactions in the home branch of the trade have been numerous. Scotch pig has been quiet throughout the week, and in one or two instances prices have been lower. Cleveland Both tin and copper are firm, and lead is unaltered. Spelter without change. Soda: cream caustic inquired for, and at £12 10s. for 60; and to 17-8d. per degree; soda crystals lower, at £4 white, at £13 to £13 5s. ; ash unchanged, at 1 13-16d. to £4 2s. 6d. ; bi-carbonate, at £9 15s. to £10 and £14 15s. for refined; saltcake, £3; glauber salts, £3. Nitrate of soda: has undergone a slight ROYAL HUMANE SOCIETY. advance, and ranges from £15 to £15 10s. Potash: muriates are scarce, and £9 158. to £10 is quoted for HE ninety-sixth report of the Royal Humane 80 per cent., F.O.B. Prussiate, yellow, 11 d. to 1s.; Society (1869) shows a balance of £239 9s. 2d. red, 1s. 9d. to 1s. 101d.; chlorate of potash, 10d. THE War Department of the Government of in favour of the society. Great activity has been Saltpetre: is quiet, but at the latter part of the week France have just given out in England further displayed by the various officers during the year; there was a better feeling; foreign, 28s. to 30s.; re-orders for tin goods to be used in the camp by the no less than 207 persons have been rescued, the fined, 34s. Alum: home consumption, demand fair; majority of whom have been immersed in the loose lump, £6 to £6 5s., and in export barrels, £7; water through the breaking of the ice in the Royal ground, at £7. Ammonia: white and grey in rather and other parks. The plans adopted by the sobetter inquiry for abroad, at £16 to £16 10s.; brown sulphate firm at £14 to £14 5s.; muriate, ciety in providing suitable appliances for the re£23 to £21; carbonate, 6d. per lb.; sal-ammoniac, covery of bodies, and their after treatment appear 42s. to 43s. firsts, and 41s. seconds. Iron salts: to be of most efficient character, great care being green and rusty copperas are dull, at 52s. to 54s.; bestowed upon the materials to keep them in work-dry, at 52s.; chloride of iron, £6; Prussian blue, ing order at all times and in constant readiness. 1s. 6d. to 2s. Copper salts: sulphate of copper, The operations of the society are not confined to £23 to £24. Arsenic at £6 15s. to £7 5s. for parks or ornamental waters in London, but to all fine powdered. Acid: tartaric is firmer, at 1s. 31d cases of drowning in any part of the globe, and to 1s. 3d.; oxalic, 7 d. to 8d.; sulphuric, at £3 5s. certificates in medals, &c., are freely distributed, to £3 15s. Magnesia: Epsom salts, at £4 10s. to after fair investigation, to all persons who succeed £4 17s. 6d. for refined. Oils: olive firm, at £48 in rescuing others from a watery grave. to £49; spindle and loom oils of good quality, in report contains some capital suggestions respect- 6s. 6d. to 7s. per gallon. fair demand; pure white Norwegian cod-liver oil, Pitch market quiet. ing medical and other treatment of the apparently Benzole: there is no alteration, 30 per cent., 28. 3d. drowned and some sound advice to persons who to 2s. 4d. Disinfectants: patent, at £5 per ton.; are seized with cramp or fatigue during swimming carbolic, at £10. China clay: 228. per ton. Pyrites one of which we print for the benefit of our very firm at 6d. to 8d. per unit; calcined Spanish, readers. It is on the philosophy of drowning, 43s. R.C. Lime: bleaching powder firm, at £9 to and says that man is the only animal that drowns £9 10s.; Super-phosphates: high percentage naturally. He does so because he is endowed quality is now largely inquired for, for next year's with reason that is to say, with a large spherical delivery; ordinary, 44 5s. to £4 10s.; mineral, 60s. brain with a skull on it which rises above his is not in such good demand, at 75s. to 80s. for 70. to 65s.; Estramadura, 1s. 2d. per unit. Manganese: If he falls into deep water, in spite of his Iron ore: hematite, prices tend upwards, and firm, great brain, he has not presence of mind enough at 16s. to 188.; oolitic, in good demand, at 6s. 9d. to stick his nose out and keep it out, as he easily to 7s. 6d. in Staffordshire. might do; but his heavy head, like a stone, presses METALS.-Iron: Scotch pig closes quiet at 51s. his nose under wator. In this position he inhales | 2d. to 51s. 3d. Cleveland firm, at 46s. for forge 4, nose. The that the French continue to get cargoes of arms THE "Times" American Correspondent declares and warlike stores from New York. The steamer "Erie " has been loading there with 115,000 muskets and other stores, and was expected to sail a fortnight ago. The North German Consul-General no longer interferes with these shipments. He says he has officially reported the departure of theso cargoes to his Government, but in reply has been instructed not to concern himself in the matter, because no portion of the law of nations prohibits such shipments. The American makers of arms and similar weapons are said to be now in the full tide of success. THE extraordinary effect in the duration of this war produced by the fortifications of Paris has drawn the attention of all thoughtful professional men to the subject of fortifying capitals generally. tion of our own War Office, and it is understood It has also, we are happy to learn, drawn the attenthat the Fortification branch there, under Sir F. Chapman and Colonel Jervois, C.B., has been directed to prepare a careful scheme for defending London. That the gentlemen who live at ease in Lancashire may not be alarmed it is well to state |