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THE

MECHANICS' MAGAZINE.

LONDON: FRIDAY, NOVEMBER 13, 1868.

CROSSING THE CHANNEL. late

DURING the height of teen the leah and Gallic shores was interrupted, and the interruption continued for nearly two days. According to a daily contemporary, the South-Eastern steamship the "Prince Ernest" made the following extraordinary voyage:-Leaving Folkestone at about 12.30 p.m., after a stormy passage, she made the harbour of Boulogne, but was refused permission to enter, the grounds for such refusal upon the part of the harbour authorities not being stated. She had not the yellow fever on board, did not sport a yellow pavilion, nor, as far as we know, is Boulogne in quarantine. Whatever the reason may be, her course was altered at the mouth of the harbour, which ought to have been a place of refuge for her instead of driving her from its shelter, and the storm-beaten vessel bore up for Calais. Arrived in the offing, and expectant of being speedily moored in safety, the surf was so violent as to forbid her availing herself of that port either. Driven to extremities, the captain, who had navigated his vessel so ably, courageously, and skilfully, abandoned all hope of landing his weary passengers upon the shores of their destination, and giving orders to put the ship about, steered for the English coast, and reached Folkestone in about twelve hours after he had started on his dangerous and futile voyage. This is the condition of the French ports upon the opposite side of the Channel. Instead of being able to afford a shelter to vessels in times of storm and tempest, they are only fair-weather ports-absolutely useless when they are really wanted, and about as fit for their duties as an outrigger would be if placed in the position of a lifeboat. And such is the result of the entente cordiale in the nineteenth century.

and side walls gave it all the aspect of a
charnel vault. After depositing the price of
the entrée, and descending into the abyss
beneath, one felt as if they had paid the toll

PREPARATION OF GUNPOWDER
WITH PICRATE OF POTASH.

to the Stygian Charon, and welcomed their THE

raposes to Whitehall, has come to grief; predient, known poehtoists ay picrate of

HE cost of any compound substance or material is undoubtedly dependent upon safe transit and emergence at the other ex- that of its individual ingredients, and theretremity as a resurrection from the valley of fore, in order to reduce the cost of the whole, it the door of death. It would be premature is necessary to diminish that of its components. to decide what may be its ultimate fate, It is well known that chlorate of potash was and whether success will attend the at one time attempted to be used in the manuefforts made by the East London Rail- facture of gunpowder, but owing to its deway Company to adapt it to locomotive tonating propensities, it was abandoned. At subway, from is employ new whether from want of funds or other cause potash. To the majority of our readers, this is immaterial for our present consideration, substance is probably altogether unknown, and the proposed similar work at the Tower although, from the name, it is manifestly a is not yet un fait accompli. We are, there- salt of potash in combination with picric fore, fully borne out in our statement, that acid. This acid is used in dyeing, and may there is not even the encouragement of a suc- be prepared by treating indigo in a pulverized cessful precedent to justify the undertaking state with nitric acid. When converted into of a project involving an enormous outlay a salt of potash, it assumes the form of briland a corresponding risk. liant needles, and, by the application of heat, Let us now glance at the bridge scheme. explodes with a considerable degree of In the first place, it will be acknowledged violence. The chemical formula of the that the only risk and uncertainty respecting crystals of picric acid may be represented by this method of spanning the obstacle is cou- C12 H2 N3 013 H O. The study of this fined to the foundations. Once they have substance and its combination with the other been got in, the difficulty is vanquished-the ingredients required to form gunpowder has task is virtually accomplished. True, that occupied M. Lissigood for a period of more they have to be got in; but foundations have than seven years, and the result of his labours been over and over again successfully got in has been to bring down the price of the salt, under considerably greater disadvantages, picrate of potash, to about tenpence a pound. and this is the encouraging fact and prece- About ninety years ago, a M. Hausmann dent belonging to the project of a bridge, treated indigo with strong nitric acid, and which does not exist for the tunnel design. obtained a product which he called "bitter When lighthouses constructed entirely of iron, of indigo." All the compounds of picric acid and supported upon iron piles, have been have an intolerably bitter taste. The subseerected far out at sea, it is absurd to talk of quent researches of Weller, Proust,Fourcroy, the great and almost insuperable difficulty of Vauquelin, Dumas, and Laurent, determined getting in foundations elsewhere in similar its composition, and gave to it a definite place situations. Besides, it would not be all the among chemical agents. It was proved to be piers that would give the same degree of identical with carbazotic and nitrophenisic trouble, but only those situated remotely from acid, and was, in fact, derived from phenic either shore. There is, in addition, one great acid by Laurent, who substituted three equiadvantage that the bridge possesses over the valents of hypoazotic acid for a similar numtunnel. Every pier of the former that rises ber of equivalents of hydrogen. By these above low-water mark is a permanent com- means he obtained, by combining it with pletion of a portion of the design, but there potassa, the salt picrate of potash, which is no such gradual accomplishment of the task assumes the form of brilliant yellow crystals, with the tunnel. Any of the four or five passing into a deep orange at a temperature lengths in which it might be proceeded would of 300deg. Centigrade, and exploding at be equally liable to destruction at any time 310deg. The salts of potash and soda preof their construction. An inroad of the sea sent many degrees of similarity; so much so, Were any demonstration of the necessity might take place at the end as well as at the that, in many instances, it demands all the of an improved method of intercommunica- commencement. So far as the time of accom- resources of an amply furnished laboratory to tion between England and France required, plishing the task is concerned, the balance is determine their identity. The picrate of we have it in the instance we have recorded. immensely in favour of the bridge. All the soda is, however, distinguished from the picrate The "Prince Ernest" had 108 passengers superstructure could be got ready while the of potash by its much readier solubility in on board, and the condition of some of them, piers were being built, and, moreover, if, owing water. after knocking about the Channel for twelve to unforeseen difficulties, they could not be The explosive properties of this salt render hours may be left to those of our readers erected cotemporaneously, any portion that it well adapted for the manufacture of gunwhose centre of gravity gets out of position was completed from either end could be used powder, and enable some important features aboard ship in stormy weather. Recognizing as a jetty, and by suitable provision in the to be imparted to it. The ordinary powder the fact that sooner or later the present con- way of lifts, the traffic could be brought to is a mixture of elements which are not, per se, ditions of affairs must undergo an alteration, the end of each shore length and transferred of an explosive character, but which, by the we may briefly glance at the means proposed to the vessel moored there in readiness. By application of heat to their mixture, become to effect the end in view without at present these means, the bridge could be utilized in both inflammatory and explosive. Their procommitting ourselves to any definite opinion the direct ratio of its progress, whereas the portions being now accurately fixed, any inrespecting their various merits. The solid tunnel could not be used until the whole of it crease of projectile force can only be obtained cmbankment scheme we renounce as a work were completed. Every year during the con- by either a mechanical effort or a superior only to be accomplished by a strong gang of struction of the former, the distance between process of manufacture. By employing the mythological Titans, or by the "slaves of the the opposite shores would be diminished, while picrates, the field of action is considerably ring," whose magic influence was all potent in the gap would remain as wide as ever, until enlarged. They possess a great force of exthe fables of oriental romance, and the the latter was finished throughout. Prima plosion or detonation, which can be increased nocturnal stories of the beautiful Schehe- facie, the idea of a tunnel nearly twenty miles by the addition of other substances, or rezade. Dismissing the idea of the solid long lying perdu at the bottom of the sea, is moderated by the employment of a sluggish union, we have the tunnel and the bridge an unsatisfactory and somewhat imaginary material, as charcoal, accordingly as may be schemes. Unfortunately for the former one, but that of a bridge occupying a visible desirable. The maximum "striking or dethere is no precedent, whereas we have and tangible position is endowed with greater structive force," so to term it, is afforded by bridges in abundance, and some of them pos- reality and security. It must also be borne a mixture in equal parts of picrate and sess piers very nearly as high as those that in mind, that whatever circumstances of would be necessary to carry a superstructure foundation and soil favour the construction of across the Channel. The Thames Tunnel the tunnel, are doubly advantageous to that cannot be regarded in any other light than of the bridge, and consequently if no difficulty that of a miserable abortion; it was a freak is to be experienced in that respect for the of one of the greatest engineers England tunnel, the argument against the difficulty ever saw, and never was fitted, in the strict of getting in the piers falls to the ground. sense of the term, for any description of The uncertain quantity in the calculation traffic whatever. It leaked at every pore, disappearing, the remainder becomes a known and the humid, dewy appearance of the roof quantity.

nitrate of potash. Probably, the best manner in which to arrive at the effects of powder upon firearms is to ascertain by analysis the composition of the result that follows the explosion of the powder. This has been done in the case of the picrates, and the advantages claimed for it are that it altogether does away with sulphur, considerably diminishes the smoke, and exerts very little deterioration upon the firearm itself. This powder is manu

factured at Bougot, and a distinguishing feature in its fabrication is that by varying the pressure to which it is subjected, the qualities imparted to it can also be varied. In addition to its application as gunpowder, it is also well adapted for the purposes of pyrotechny. M. Lissigood has produced some remarkable varieties by combining the salt of potash with other ingredients. A brilliant gold colour of great vividness is afforded by mixing fifty parts of picrate of potash with the same proportion of picrate of iron. By combining forty parts of picrate of ammonia with sixty parts of nitrate of baryta, an intensely green colour is produced; while the proportions of fifty-four parts of the former material with forty-five parts of nitrate of strontia give rise to a bright red light. There is, however, nothing new in these results so far as baryta and strontia are concerned, for their effects are well known to the pyrotechnist of the

No matter whether the

mences applied geometry, mechanical draw- thing, a little worse.
ing, and mechanical and chemical technology. columns relative to the number of interrup-
Here, too, he varies his studies, according as tions, their duration, or their proportion to
he is destined either for engineering or chemi- the mileage, be looked at, but little difference
cal pursuits. In the last class, he goes through can be seen. This is really what might be
the highest branches of mathematics, studies expected. At the date of the first returns,
foreign languages, and completes his know- 1862, things in India relative to telegraphs
ledge of applied chemistry. There is also in might be safely stated to be almost as bad as
Chemnitz a workmasters' school, where the they could be-lines badly constructed,
pupil receives much the same education, but wretchedly insulated, and work scamped in
of a more practical character. Of course, all every branch and direction by the natives.
this is done under the direction and with the What could be expected? Year after year,
assistance of the State. Public education, it until the date of the reports we are now ex-
is said, has reached the highest point in amining, things went on quietly in the same
Saxony; and if the condition of Chemnitz groove. We cannot, therefore, be surprised at
is one of the results, an example is offered corresponding results being arrived at, and
which it would be well for us to copy. one may really wonder that things were not

TELEGRAPHS IN INDIA.

most humble pretensions. Anyone who has WE bring the subject of the Indian telegraphs to a conclusion in our present witnessed the pyrotechnic displays at the number, with some particulars as to the Crystal Palace, and the feu d'artifices in amount of interruptions of communication, Paris, must be well aware to what astonishing and the plans that have been adopted since perfection the art has been brought. In fact, the date of the returns to render them less it is nothing more than printing and illustrat- frequent and lasting. From the numerous ing by fire, for there is not a device or motto reports handed in, a statement has been comof any kind that could not be produced in piled, showing various particulars as to the letters and figures of light if required. It is interruptions and their duration, tabulated rather curious that notwithstanding the dis- under their respective divisions for the years coveries of science, and the invention of from 1862-63 to 1865-66. From this statemechanical art, the composition of gunpow-ment, the following table has been prepared, der, with respect to the mere ingredients, showing a comparison between the years have remained identically the same since its 1862-63 and 1865-66 of the number and introduction as a destructive element. Whe- duration of interruptions, and their proporther the employment of the picrates will tion to mileage. eventually bring about any material change, remains to be seen; but unless it possesses very superior merits, it will not easily supersede any of the well-tried ingredients of the

chief element of modern warfare.

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The mileage at the end of 1862-63 was 11,350 miles, and at the end of the year 1865-66 as much as 2,040 miles had been added, but the columns given to proportion to mileage have been properly reduced, so that the comparison will be fair :

to

Division.

COMPARATIVE RETURN OF INTERRUPTIONS between the years 1862-63 and 1865-66.

Total Number of Interruptions.

1862-63.

May, 1865,

to

Aggregate Duration.

Proportion of Interruptions to Mileage.

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Jan. to

May, 1865,

Jan., 1866. Apr., 1866.

1862-63.

to

1862-63.

May, 1865, Jan. to Jan. 1866. Apr., 1866.

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18.89

Punjaub

397

10-439

21.94

...

Bombay

133

49

2.856

7.178

10.74

15.45

4.87

East Coast

115

27

2.345

13:19

3.11

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760-9

...

...

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Chemnitz may be called the Nottingham of Saxony; but besides the hosiery for which it is justly celebrated, a large quantity of spin.. ning machinery and hardware is manufactured there. It is one of the most thriving towns on the Continent, and the population increases with extraordinary rapidity. Still, when the last census was taken (1861), the number was only about one-third that of Nottingham. The artizans are a singularly thrifty people. A large proportion of them possess freehold cottages with gardens, which they cultivate when the looms are slack. It would be interesting to compare the educational opportunities of a boy in Nottingham and Chemnitz; but at the former we believe there is nothing in the way of technical education to be had. At Chemnitz, however, a boy of fifteen possessing the knowledge obtainable at an ordinary school, may enter at what is called the Gewerbschule, where, for about two pounds a year, he receives an education which will fit him scientifically for any skilled employment. Entering the lowest class, he continues the study of his native language, studies arithmetic and geometry, If the foregoing statement be examined, it physics, general chemistry (organic and in- will be found that there is not much differorganic), freehand drawing, and book-keeping. ence between the two years. Although an inThe pupil is allowed to vary his course some-terval of three years separates the two statewhat, according to the employment for which ments, it cannot be seen that any improvement he is destined. Advancing to the next class, he has been effected in the meantime; we can goes on with his mathematical studies, com- only find things much in statu quo, or, if any

Bengal

გი

...

Malabar Coast*

Rajpootana*.

Bangalore

worse.

However, it would be decidedly unfair to compare faults and their duration out in

India with interruptions in Europe, where the nature, and especially the position, of telegraphs are so entirely different. But still there is one point that is in favour of certain portions of India, that lines can at stated times be worked through with but little or no insulation, whilst in England, that at no time is possible. In fact, if it had not been for the climate, there were certain portions of line in India that, from the almost entire absence of insulation, would never have been worked through at all.

The number and extent of the interruptions are due in a great measure to the exceptional nature of the country through which the better than to quote Colonel Robinson, R.E.: wires pass. On this point, we cannot do "It is evidently not possible to preserve lines of such enormous extent as those of India from occasional interruptions. In the wild forest tracts, such as those of Assam, Arracan, Ceylon, or the south of India, trees will fall and grass and creepers will grow in spite of the utmost care. Wild elephants will occasionally cross the lines and knock down the posts, whilst no part of India is exempt from the violence of tropical thunderstorms and gales, all of which are sources of interruption to telegraphic communication. Imperfect communication is another evil to which all telegraphic lines are liable, and with which the department will have to contend at great disadvantage for some time longer. Cases of this nature are partly due to bad insulation and wire, and partly to the growth of vegetation in the immediate proximity of the wire."

son,

Relative to the unfairness of comparison between India and England, Colonel Robinsays In England the lines are generally erected by the side of the railway, with offices at short intervals; the length of the interrupted portion must, therefore, always be short, whilst the facilities for travelling along the line are very great. In India, whilst the intervals between stations are ten times greater, the facilities for travelling rapidly from one to another are comparatively three or four times less. Let allowances for these differences be granted, and I am quite confident that the Indian lines, when insulated and doubled, will work as well as any in the world-perhaps better."

Let us now glance at some of the steps that have been taken to remedy these evils and improve the means of communication. Colonel Robinson immediately on his accession to office, although, as he states, "that previous to July, 1865, I not only had no connection with, but positively knew nothing whatever of the working material, antecedents, or organization of the department," yet he appears from the earliest date to have intuitively grasped the defects of the department, and set himself energetically to work to remedy those defects, reorganize the system, and do all that could be done to thoroughly improve the communication. Instead of the old insulation, or, rather, the want of insulation, the various important trunk lines were started at once with reinsulation,

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and, where required, with double wires, not in the that way lines were formerly doubled, where, owing to the badness of insulation and facility of conduction from wire to wire, "contact" was established, and communication could only be established by leaving the second wire alone.

Europe to England. As these times are
taken from messages from various points of
India, passing through the Indian system, it
cannot but be a matter of great congratula-
tion to acknowledge that the telegraphic com-
munication has most sensibly improved, and
that the steps taken to ameliorate the system
have borne good fruit.

STEAM LAUNCH FOR THE SULTAN

OF TURKEY.

THE necessity of some more rapid means
THE of

sons.

This

degree of perfection; they have nine of these useful vessels already built or on hand.

Yesterday, the launch left the Temple Pier at 11 hours 24 minutes, and arrived at Twickenham at 1 hour 30 minutes. Twenty minutes were consumed in stoppages on the way, which brought the time to 1 hour and 46 minutes for the run of 174 miles, or 10 miles an hour, the tide serving part of the time. On the return journey, the run from Richmond Bridge to Kew Bridge, a distance of two miles seven furlongs, was made in 20 minutes, fair steaming and careful navigation, to avoid the shallows which abound in that locality. This trip is highlybound factory, and bears testimony to the character of Messrs. Yarrow and Hedley's craft, which, although not built for extreme speed, yet gives result which larger vessels may envy.

a

PHOTOGRAPHY.

PHOTOGRAPHIC

A NEW ELECTRIC LIGHT-PRINTING
TRANSPARENCIES BY ARTIFICIAL LIGHT.

T one of the soirées of the British Association,
at Norwich, Mr. John Browning, F.R.A.S.,

We have already alluded to the change in the reorganization of the staff, but the most important change has been most certainly in the infusion of new and competent element in the staff. Formerly, the Indian staff was on such a footing that the appointments occasionally offered to competition in England met with but little encouragement, but now a large number of appointments are con- selves and with the shore has lately given stantly being made. Each time the nomina- rise to a class of tenders, better known as tions exceed the number. of appointments; steam launches. The most recent example of and after a rather severe examination the this description of vessel is one designed and required number are passed, but not, as here- constructed by Messrs. Yarrow and Hedley, tofore, to proceed directly to India, but to engineers of the Isle of Dogs, Poplar, and undergo a lengthy and fitting course of study; which made a highly successful trip yesterafter which, the nominees, if successful in day from London to Twickenham. their examination, are drafted out to India to launch has been built and fitted for the Sultan infuse a new and vigorous element in the of Turkey, and is intended to convey Governsystem. The studies the nominees have to ment despatches to the shipping on the Bos-A go through are, in the first place, a general phorus. This boat is built of teak, and is course, more particularly embracing natural 35ft. long x 6ft. 6in. beam. She is fitted the optician who manufactured the great telescope philosophy, and especially mathematics, right fore and aft with seats, and will accom- for the Government of India to photograph the chemistry, and electricity; the final course modate comfortably sixteen or eighteen per- late eclipse, showed us a new electric lamp, inof study is one of practical telegraphy, which is the one above all their attention ward end of the boat, and the machinery is cells only. With such weak power, we had no The passengers are carried at the for- tended to be worked by a Grove's battery of six should be thoroughly directed to, and we cannot but think that too little time is placed aft. An awning reaches from end to doubt that the lamp would "spit" and flicker congiven to this subject. Their special avoca- the engines from the weather. The engines value. Last Monday night, however, upon going end so as to protect both the passengers and siderably, so considered the instrument of little tion being telegraphy, more time might be consist of two inverted cylinders driving given to its study than to the rest. Up to the direct on to a crank shaft in the usual man- to see the lamp in action, in consequence of reports present, the nominees have passed their tele-ner; the valve gear is placed between the praphic pupilage under Mr. W. H. Preece, two cylinders; and the feed pump is worked at Southampton, where they have undergone off the forward engine piston rod crosshead. a thorough course of practical instruction. Line work, instrument, and everything prac-motion is well deserving of notice, as it apThe arrangement for working the link tical, have been instilled into them, and more permanently rooted by their having to do all pears to be specially adapted for this class of In ordinary lamps, the carbon points are pulled craft, owing to its extreme simplicity and the themselves. The supply of a quantity of control it enables the man at the helm to magnetic apparatus, that distance being sufficient a limited distance apart by automatic electrostores from the India Department has enabled have over the engines. Attached to the after to give the maximum of light without breaking that practical instruction to be given to them cylinder is a brass hand wheel connected the flow of the current. In the new lamp, there which it were otherwise difficult to do; poles with a right and left-handed screw, and by is no pulling apart of the carbon points, the bathave been erected in their proper position, this means the lever in direct connection tery power being so weak that all such movements insulators fixed, wires jointed and run up with the links is raised or lowered. By turn- would be useless. The principle adopted in the in fact, a complete aerial telegraph has been ing the hand wheel, the engines are started case before us is to let the carbon points touch fixed by their own hands; and instruction or stopped, or are regulated to work at any that the current has to burn an interval between each other, and to clamp them in that position, so given them as practical experience cannot grade of expansion and consequent speed the two points for itself. In the accompanying but have a deep, lasting, and beneficial effect. that may be desired. The propeller is of cut, D D is a brass rod carrying the upper carbon The construction and manipulation of instruments, and of testing generally, has been also three blades of 5ft. pitch. The boiler is gun metal, 2ft. 4in. diameter, and having included. Gentlemen instructed in such a vertical tubular, lugged with mahogany, and manner are sure to make themselves of ser- provided with the usual fittings. The pipes vice when they arrive out, and tend to bring connecting the engines and boiler are throughabout the result of improvement to the Indian system. That the various plans adopted for The official trial trip of this vessel took the improvement of the telegraphic commu- place last Monday, when she left Messrs. nication in India have borne fruit, we may Yarrow and Hedley's works at 1 o'clock, for give the following figures as some test. Greenhithe, arriving back at 4.40 p.m., comFrom May, 1865, to February, 1866, the average maxima and minima times of trans-pleting a distance of 31 miles in 3 hours 40 minutes. The day was very stormy, mission to and from Calcutta and Bombay and, under these circumstances, to have

were as follows:

Calcutta to Bombay.

Maxima

hr. min.

Bombay to Calcutta.
hr. min.
35 47

59 15

11 50

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11 43

out of copper.

maintained a continuous speed of over eight
miles an hour is a very satisfactory result for
a boat of this size. In calm weather, a steady
working speed of nine miles an hour can be
well kept up, as was shown by the trip yes-
terday. The engines indicated from 9 to 90-
horse power, and the consumption of fuel
when running full speed was about 70lb. of

afloat as to its steadiness, a little examination
made it apparent that the new lamp will be a for-
midable rival to the lime light, for lecturing and
upon an entirely new principle.
other purposes. In fact, the lamp is constructed

A

Minima Mean. 35 32 23 45 The above times are the average of ten months. We cannot make an exact comparison for the present time, but of the messages received in London from India, from coal per hour. Calcutta, Madras, and Bombay, the averages As already observed, this boat is going to are as follows:-The minimum time occupied the Mediterranean for carrying Government by a message from the presidency towns of despatches, and she has been built to stand India was, in September, 12hr.; October, moderately rough weather; she is to be trans12hr. The average time occupied, via ported, with all the machinery in her, on the Turkey, from the same points was, in Sep- deck of a vessel, thereby requiring nothing tember, 1 day 16hr. 15min.; October, 1 day of any kind to be done on her arrival out, 20hr. 38min. Compare these with the pre-except to fill the boiler and get up steam. point, and sliding easily in its vertical bearings by ceding figures, it will be found that the The advantage of sending machinery abroad its own weight. Directly the upper point touches minimum times agree exactly, whilst the entire cannot be over-estimated, as it so fre- the lower one, the current is established, and the little electro-magnet A at once pulls down its average differ but slightly. On the one hand, quently happens that work is condemned armature, which clamps the upper brass rod we have times of transmission between two through faulty erection. Messrs. Yarrow and at B. Directly the current is broken by the presidency towns in India, and in the other Hedley have expended a great deal of time wasting away of the carbons, the electro-magnet from those two towns and others not only and money in experiments with steam A ceases to hold the brass rod, which then falls, through India, but through Turkey and launches, having brought them to a very high and re-establishes the communication. Nothing

can be simpler. At the first glance, it would be thought that an arrangement like this must give a light which would "spit" and flash with great vigour. Yet the light produced is as steady as a gas flame, or the light from incandescent lime under the oxy-hydrogen blowpipe. As a matter of fact, the current does meet with constant interruptions, yet the distance between

next annual election. The following papers were
then read :-

ON THE FURTHER UTILIZATION OF THE WASTE
GAS FROM BLAST FURNACES, AND THE ECONOMY
OF COKE DUE ΤΟ INCREASED CAPACITY OF
FURNACE.

other means, with a permanent pressure adjusted
to give the exact amount of adhesion required for
transmitting the limit of driving power desired ;
and for the purposes of friction brakes, the com-
pression of the discs is effected by a hand lever, so
as to apply the power of the brake to the extent
required at any moment. In either case, the
amount of frictional adhesion can be increased to

the carbons is so small, that the current immediately blast furnaces in the Cleveland district, the waste any required extent by employing a sufficient

recommences its passage, so that in accordance with the law of the persistence of vision upon the retina, the instantaneous interruptions in the light cannot be recognized by the eye. With attention, the ear can detect the vibrations of the upper car

bon, but the noise is very slight. The light itself stoves, it is of importance to utilize the whole of numerous aud varied, extending up to large ships'

does not consist of an infinitesimally small spark between the electrodes, but the two carbons are hented for a short distance from their extremities. All who are practically acquainted with the use of the lime light for photographic enlargements, or lecturing purposes, know that gas-bags will only keep in good working condition a short time, and

are very expensivo in first cost. Gasometers are

small, it will not do to use in a lantern with bad

screen.

By Mr. CHARLES COCHRANE, of Dudley.
WITH the increased capacity of the present large
gas given off from the furnace is so far im-
poverished, both in quantity and quality, that, in
order to maintain a uniform supply of gas for heat-
ing purposes at the steam boilers and hot-blast
the loss of gas hitherto occurring at the times of
the gas given off from the furnace, by preventing
lowering the closing cone or bell for charging the
materials at the top of the furnace. Although the
the open mouth of the furnace is not long at each
time during which the gas can thus escape through
lowering of the bell, the entire loss of gas amounts
to fully 6 per cent. of the total quantity of gas
evolved from the furnace; and the escape of the
tion in the supply for heating purposes, and a
gas at the furnace mouth occasions an interrup-
liability to explosion on restoring the supply of
gas at the boilers and stoves. These objections
have been obviated by the writer by a plan of
doubly closing the furnace top, the ordinary closing
bell and hopper being completely closed in by the
addition of an outer cover, containing flap doors,
through which the charging materials are filled

number of discs, so as to avoid subjecting them to
a degree of pressure severe enough to occasion
wear of the rubbing faces.
brake to hoists, windlasses, and shafting are very
The applications of this friction coupling and
than thirty tons on a ship's cable; and descrip-
windlasses, holding safely under a strain of more
tions were given of several of the principal appli-
cations, illustrated by working models and speci-
sacks, &c., the drum containing the wood discs
mens. In the case of light hoists, for raising
forms the chain barrel, and runs loose upon the
main shaft carrying the iron discs, which is pre-
vented from turning backwards by a ratchet wheel
fits upon a screwed portion of the shaft at the outer
and pawl. A hand rope wheel, with screwed boss,
end of the series of friction dises; and on turning
this wheel in the direction for raising the load, it
traverses endways along the screwed shaft until it
has compressed the discs together with force
enough to give sufficient frictional adhesion for
raising the load. On turning the hand wheel back-

releases the discs from pressure; and the load
the pressure again upon the discs through the

hand wheel.

objectionable for their want of portability, and the
trouble of emptying and filling them with large
volumes of water as well as gas. This new lamp
is, therefore, likely to be a formidable rival to the
lime light. As the size of the new light is very
condensers, because the spots and striae in the
glass would then be projected in a visible form
upon the screen. In fact, its use will necessitate
the adoption in the magic lantern, both of good into the hopper. These doors are closed at the wards, the unscrewing of the wheel on the shaft
lenses and good pictures, since imperfections in
these are always most conspicuous when a small time of lowering the bell for dropping the charge then runs down freely, until stopped by applying
and brilliant light is adopted in the lantern. In into the furnace, so that the only escape of gas
the cut, the lamp is pictured as furnished with that can take place is a quantity equal to the ca-
a parabolic reflector. For lantern purposes, this pacity of the hopper at each time of lowering the
Another form of hoist is also constructed, in
This plan
cannot be used, and Mr. Browning is going to sub- bell, which is insignificant in amount.
which the load is prevented from running down
stitute a small concave silvered reflector, of such of closing the furnace top has now been in suc-
a curve as to give the maximum of light without cessful operation for nine months at the Ormesby freely, and can be lowered only by continuing the
Iron Works, Middlesborough, and continues to this case, both the chain barrel and the hand wheel
process of turning the hand wheel backwards. In
indistinctness in the image projected upon the
work most satisfactorily. The economy of coke
Photographic transparencies on glass for the due to increased capacity of furnace is shown by run loose upon the main shaft, which is prevented
magic lantern are usually printed in the copying above works, having an internal capacity of only wheel engage with each other by a spiral clutch,
the working of one of the original furnaces at the by a ratchet wheel from turning backwards; and
the contiguous faces of the chain barrel and hand
camera, unless dry plates be used in the work. about 7,000 cubic feet, as compared with that of consisting of a single turn of a very slow spiral.
Much time and trouble is saved by printing these the larger furnaces at the same works, having a The outer face of the hand wheel is a plain disc,
pictures upon wet plates by superposition, but then
the edges of the negative and the wet plate, to keep/Consumption of coke per ton of iron made is against an equal disc on the ratchet wheel keyed
a few folds of paper or card must be placed between capacity of about 20,000 cubic feet. The average of larger diameter than the chain barrel, rubbing
them from touching, or the former would be spoilt less than in the small furnace; and at the same upon the main shaft; and the outer face of the
by the nitrate of silver solution. Gas light is often time, the waste gas from the larger furnace is chain barrel is also a similar plain disc, rubbing
used to print such pictures, but the length of the evolved at a temperature of only about 560deg. On turning the hand wheel forwards, for raising
against another disc secured upon the main shaft.
flame introduces a certain amount of parallax, Fah., or 110deg. below that at which it leaves the the load, the inclined surface of the spiral between
because the printing must be done within a foot or smaller furnace, on account of the heat of the
two of the burner. Practically, at a distance of
two feet, if the negative and wet plate be held gas being taken up to a greater extent by the the hand wheel and chain barrel tends to separate
steadily in one position, there is no visible loss of materials in the top of the larger and higher fur- them endways, and thus produces an end pressure,
The causes were explained that account tightening together the external plain discs with
sharpness from parallax, and the operator who
the pressure required to produce friction enough
tries this plan will find that a copying camera is for the economy of fuel in the large furnace; and for raising the load. For lowering the load, the
assuming that, by further enlarging the capacity hand wheel being turned backwards withdraws one
not such a necessary in printing transparencies as
of the blast furnace, the further reduction of tem- incline from the other in the spiral clutch, and
it is commonly supposed to be. Nevertheless, aperature effected in the gas taken off would be in
light emanating from a point must be more per- the same proportion as the reduction already ob- thereby releases the friction discs from pressure,
fect for such purposes than a broad or high flame; tained with the present increased size of furnace, the load can only take place so long as this with-
so that the load can descend; but the descent of
so the new electric lamp is likely to be useful for it was shown by calculation that the extreme theo- drawal of the inclines is continued by the hand
this purpose also.
would be reduced to the temperature of the ex-
retical limit of economy, when the escaping gas wheel continuing to be turned backwards, allow-
ternal atmosphere, would be reached by increasing the chain barrel to follow; and the moment
ing the capacity of the furnace to about three the hand wheel is stopped, the inclines become
times that of the present large furnaces in the tightened again upon each other by the load acting
Cleveland district, provided that no practical dif-

A safer, or cleaner, or better illuminating power than the lime light can scarcely be found by those who are experienced in its management, and with such people the question of the adoption of the new light resolves itself into one of cost, brilliancy, and portability. As regards portability, the apparatus connected with the new light has immensely the advantage. As regards brilliancy, we think, from the experiments of last Monday, that with a proper reflector, and a battery of eight or nine cells, a 9ft. disc can be well covered with an intense light. As regards cost, we have not sufficient data to draw a comparison, but the difference between the two cannot be great. In the hands of inexperienced persons, a dangerous explosion is no uncommon thing with the lime light, and in the preparation of oxygen, neither of which risks are encountered in using the electric light.

INSTITUTION OF MECHANICAL
ENGINEERS.

THE of mom, love this,
HE general meeting of the members of this In-

in the lecture theatre of the Midland Institute,
Birmingham, Frederick J. Bramwell, Esq., Vice-
President, in the chair.

The secretary (Mr. W. P. Marshall) having read the minutes of the previous meeting, several new members were elected, and the officers of the Institution were nominated by the meeting for the

26 cwt. in the larger furnace, being 14 per cent.

nace.

ficulties interfered.

ON AN IMPROVED FRICTION COUPLING AND BRAKE,
AND ITS APPLICATION TO HOISTS, WINDLASSES,
AND SHAFTING, &C.

By Mr. THOMAS A. WESTON, of Birmingham.
THIS friction coupling and brake is composed of
alternate discs of iron and wood, threaded upon a
shaft, and pressed together laterally with sufficient
force to produce the requisite amount of friction
between their contiguous flat faces. The iron
discs slide longitudinally upon a feather on the
shaft, so as to revolve with the shaft; and the wood
discs are not connected to the shaft, but are held
at their outer edges within an external casing or
drum, so as to revolve with the drum, while
capable of sliding longitudinally within it. By
this arrangement, when the entire series of discs
are compressed together longitudinally, the fric-
the pinout disos in teltiplied by the total number
tion produced between the contiguous faces of any

of discs; and thus, by increasing the number of
discs employed, any desired increase may be ob-
tained in the extent of frictional area, without any
reduction in the pressure per square inch upon the
rubbing surfaces. In applying the series of discs
to the purpose of friction couplings for shafting
they are compressed together by set screws or

on the chain barrel, which is thus jammed end-
ways between the friction discs, preventing the
load from running down further. This arrange-
ment accordingly provides the means of lowering
the load with perfect safety, avoiding the risk of
injurious jerks on the chain.

ON THE MOULDING OF TOOTHED WHEELS, AND AN
IMPROVED WHEEL MOULDING MACHINE.
By Mr. GEORGE L. SCOTT, of Manchester.
THE object of the machine is to afford the means
of obtaining strictly accurate castings by machine
moulding, with a portable and self-contained ma-
chine of small cost, capable of being readily and
quickly applied at any part of a foundry. The
whole machine is carried upon a centre pillar,
which fits into a socket in a cast-iron pedestal,
sunk in the floor of the foundry below the depth
required for moulding, and fixed truly vertical;
several of these pedestals are placed in convenient
situations in the foundry floor, so that the mould-
the moulding of different wheels.
ing machine can be employed successively upon
The centre

pillar of the machine carries a horizontal arm,
capable of adjustment radially to suit the diameter
of the wheel to be moulded; and the extremity of
the arm carries a vertical slide, on the bottom of
which is fixed the pattern for moulding the teeth
of the wheel. This pattern consists of two teeth
only, for moulding one space only at a time,

1

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BOILERS.

whereby absolute equality is ensured in the size,required shape, working round a centre pin fixed and shape of all the teeth in the wheel. After n the same podestal which afterwards carries the KENDRICK'S IMPROVEMENTS IN STEAM moulding each tooth, the pattern is drawn from centre pillar of the moulding machine, so as to the sand with perfect steadiness by the vertical nsure strict accuracy for the whole of the work. slide of the machine; and by means of a set of The important practical advantage is afforded by change wheels and a worm wheel keyed upon the machine moulding of greater accuracy than can be centre pillar, the radial arm is turned round attained by patterns, together with an unlimited through a space equal to the pitch of the teeth, variety of dimensions, pitch, and forms of teeth, so and the pattern is then lowered again for mould-as to meet exactly the requirements of any case ing the next tooth of the wheel. On the com- that may occur, without being restricted to some pletion of the whole of the teeth, the moulding machine is lifted off the pedestal by the foundry crane, the cores for the arms are put in their places, and the top box put on, ready for casting; the flat surfaces of the top and bottom boxes having been already prepared, before the moulding of the teeth was begun, by means of strickling boards of the

existing range of patterns, and without incurring
the cost and delay attending the preparation of a
new complete pattern. A specimen of the mould-
ing machine was exhibited and shown in operation,
together with samples of spur and bevil wheels
moulded by it.

The meeting then terminated.

T has long since become a recognized principle in boiler construction that to break up the mass of water into small portions is to prevent serious accident from explosions, to economize fuel and space, and to promote the circulation of the particles of water. This principle has been carried out to a very successful issue by Mr. I. Kendrick, of the Atlas Boiler Works, Victory-place, Rodney-road, Walworth, in the boilers illustrated in the accompanying engravings. These show two principles of construction adopted by Mr. Kendrick, one of which is a recent notion, and the other an older invention of Mr. Kendrick'

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