Abbildungen der Seite
PDF
EPUB

oven, built expressly to contain it, and where it will remain for the next two months, which time will be necessary for that gradual cooling process to which it must be subjected. It is fine thing to see a man of Lord Rosse's station, instead of applying a strong mechanical genius, as is often the case, to nicknackeries, at once attacking the most important and arduous problems, and forwarding the highest branches of science. During the very delicate and difficult experiment of yesterday, he was perfectly cool and decisive, and amidst various suggestions from the bystanders, quietly followed his own judgment, which was better than any of them. His present achievement, should it finally prove quite successful, is of the greater value, since the mere expense is quite beyond the reach of an ordinary professional man. This last operation, after having satisfied himself of the manner and practicability of each part of the proceeding, could not have cost him less than £1,000. If the final result proves satisfactory, which there seems no reason to doubt, he will have reached, in the opinion of scientific men, the maximum of effect that is attainable, since the eye, as they affirm, could not make use of a larger speculum than about 6 feet diameter."

Great Colliery Tunnel.-The Victoria Tunnel, constructed for the conveyance of coals from the Leazes Main Colliery, and Spital Tongues Colliery, to the river Tyne, near the Glass House Bridge, Ouseburn, has been completed, after a labour of two years and ten months. The tunnel, which extends under the Barras Bridge down the Dene, is two miles and a quarter long, and seven feet six inches high; it has been constructed, at a great expense, by Messrs. Porter and Latimer, the owners of the Leazes Colliery, to enable them to ship their coals on the Tyne. The engineer is Mr. Gilhespie, who has displayed great skill and perseverance in conducting this great undertaking to so successful and satisfactory a termination.-Mining Journal.

Electric Dyeing.-Mr. Baggs has discovered a method of applying the oxides of various metals to the purposes of dyeing cotton cloths by the agency of electricity. He showed, last week, at the Polytechnic Institution, an experiment or two to prove the practicability of his invention.

Experiments with Jeffery's Adhesive Composition. -Amongst the numerous inventions submitted to the Lords Commissioners of the Admiralty, and referred by their Lordships to the Committee of master shipwrights recently sitting at Woolwich dockyard, was a composition to be used in place of the substance with which vessels are at present caulked, to render them water-tight. The experiments ordered to be made by the master shipwrights to ascertain its value when applied to the purpose for which it is intended, and the result, are interesting and satisfactory. Two pieces of African teak, a species of wood difficult to be joined together by glue, on account of its oily nature, had a coating of the composition applied to them in a boiling state, and in a short time afterwards bolts and screws were attached to each end, the joined wood placed in the testing frame, and the power of Bramah's hydraulic engine applied to the extent of 19 tons, when the chain broke without the slightest strain being susceptible where the joining took place. A larger chain, of one inch and a half in diameter, was then applied, which broke with a strain of 21 tons, the joint in the wood remaining apparently as firm as at first. The utmost strain the cement can bear in this form, therefore, remains to be proved when experiments are made with larger chains.

Four pieces of hard wood were then joined together, weighing in one piece 44 cwt., and carried to the top of the shears in the dockyard, a height of 76 feet, from which it was precipitated on the hard granite wharf wall below, without any of the joints yielding in the smallest degree. The result of these severe tests induced the Lords Commissioners of the Admiralty to communicate with LieutenantGeneral Sir George Murray, G.C.B. and G.C.H., for the purpose of making experiments with it in the marshes, by bringing the full force of cannon balls against it. Accordingly, a number of planks of oak 8 inches thick and fir 16 inches square were joined together with the cement, to represent 8 feet in height and eight feet in length of the side of a first-rate ship of war, without any thing else in the shape of bolt or security to assist the composition; and it was, on Tuesday, set up as a target at the butt in the marshes. Three new 32-pounder guns were placed at 400 yards distance or point blank range, and three shots fired. The effects were wonderful, tearing the wood to pieces, and in only one instance, where the joint had not been good, showing that they had any effect upon the cement, so as to sepa rate the joined parts from each other. A hole xix inches and a quarter in diameter was then bored in the centre of the target and a 32-pounder shell inserted, and exploded by a match, which tore the wood to small splinters without in many places in the least separating the composition. This new invention is said to possess the power of expanding like India rubber in warm climates, and will not become brittle under the coldest temperature.-Times.

Magnesian Cement.-The valuable properties of magnesia, in the composition of hydraulic cement, were first brought to the notice of the Madras Government by Dr. Macleod, and applied in reparstions of the fort in 1825. About a twelvemonth afterwards, a comparative trial was made between a cement of the calcined mineral mixed with sand, a cement of lime and ironstone, and common chunam plaster, applied to portions of the same wall. After a heavy monsoon the magnesian cement was found to be the hardest and strongest of the three; and was thought to be fully equal to Parker's cement. The price at which the two cements could be procured at Madras was then equal; but, chiefly in consequence of the discovery of large deposits of the magnesia on the banks of the Cauvery, near Trichinopoly, the magnesian cement can now be produced at less than one-sixth of its cost at that period. A claim to the discovery of this mineral was made a few years ago by Col. (now General) Pasley, who was unacquainted with Dr. Macleod's experiments; but on an investigation of the matter, made by the authorities in England, the claim of the latter gentleman was clearly proved, and a handsome donation of 3009 rupees was made to him by the East India Company. -Lieut. Newbold.

Intending Patentees may be supplied gratis with Instructions, by application (postpaid) to Messrs. J. C. Robertson and Co., 166, Fleet-street, by whom is kept the only COMPLETE REGISTRY OF PATENTS EXTANT (from 1617 to the present time). Patents, both British and Foreign, solicited. Specifications prepared or revised, and all other Patent buiness transacted.

LONDON: Edited, Printed, and Published by J. C. Robertson, at the Mechanics' Magazine Office,
No. 166, Fleet-street.-Sold by W. and A. Galignani, Rue Vivienne, Paris;
Machin and Co., Dublin; and W. C. Campbell and Co., Hamburgh.

[blocks in formation]

Mechanics' Magazine,

MUSEUM, REGISTER, JOURNAL, AND GAZETTE.

No. 977.]

SATURDAY, APRIL 30, 1842.

Edited, Printed and Published by J. C. Robertson, No. 166, Fleet-street.

[Price 3d.

[graphic]

VOL. XXXVI.

[ocr errors]

HOLCROFT'S PATENT PORTABLE SAFETY BOAT OR PONTOON.*

To a people so eminently and essentially maritime as the English nation, an invention which gives additional safety to mariners and others, who are led by the necessities or the vicissitudes of life to traverse the ocean, cannot fail to be regarded with deep interest by the whole community.

The vast increase that has taken place of late years in the numbers of those who daily seek that occupation and subsistence in the cultivation of land in the colonies which are denied to them on their own soil, renders it a matter of the highest importance to ensure to them during their passage to the distant shores of Australia or the Canadas, a greater degree of safety than now unfortunately has been found to exist; so that in case of any sudden disaster at sea, and whilst distant from any human aid, the mariners may be able to command within their own vessel the means for ensuring an escape from the horrors of a death by drowning, or the still more horrible one of destruction by fire.

The instances, far too numerous to particularise, which are on record of the loss of human life at sea, arising from the destruction of ships by fire or water, offer one melancholy reflection to the observer-namely, that the majority of these fatal occurrences have been the result of an insufficiency of boats, wherein the crew and passengers could seek a temporary refuge; and it has hitherto been found totally impossible to remedy this evil, inasmuch as the bulkiness and unaccommodating form of the boats at present in use render it a matter of difficulty to find safe stowage even for the scanty and limited number that are at present to be found on board of merchant and passenger ships. The consequence of this inadequate supply of boats has been, in most cases where the number of passengers and crew has exceeded that which the boats could contain, to occasion the most awful and desperate struggles for priority in obtaining a place in the boats; which has in some cases ended in the swamping of the boats, from the multitudes that rushed into them in the hope of escaping death: or else in a

• Patent dated October 28, 1841; Specification enrolled April 28, 1842.

catastrophe still more frightful to contemplate, namely, the violent ejection or murder of the weakest, in order to lighten the overburdened barque-as was seen not very long ago in the case of the American ship William Brown, the crew of which saved themselves in this horrible manner at the expense of the lives of those whom they were bound to protect and to save, even to their own detriment.

66

It needs, therefore, no very elaborate exordium to prove that at the present the principal reliance for the safety of those who go down to the deep in ships," is more in the protection which a gracious and ever-merciful Providence is always ready to afford his creatures, and in the goodness of the ship, and skilfulness in the mariners, than in any hopes of escape by means of the boats which are carried on board emigrant and merchant vessels. The invention, therefore, of a boat which should combine portability, capacity, lightness of draft, capability of being contained in a small compass, and unconquerable buoyancy, and which to those essential qualities should add that of being economical in its construction, both in materials and labour,-has long been a desideratum.

Many persons have obtained patents for inventions within the last fifty years, purporting to be boats for the preservation of life in shipwrecks and storms; and the four quarters of the globe have furnished those who have engaged in the endeavour to construct such a boat, with models of various degrees of merit: but hitherto, notwithstanding the numerous efforts that have been made, nothing which can really claim to be successful has as yet been achieved. The Greenlander, the Esquimaux, in common with the fisherman of the Coromandel coast, have furnished their leathern skiffs, or their fibre-sown massoula boat, as models; and the results, as exhibited in the life-boats of Captains Manby, Basil Hall, and many others, have been so far good that they have replaced the clumsy fabrics that were formerly in use for the purposes to which they are applied. Still there remains to be overcome the hitherto insuperable difficulty of furnishing a cheap, safe, light and portable boat, which shall serve the purposes of the mariner

HOLCROFT'S PATENT PORTABLE SAFETY BOAT OR PONTOON.

whilst engaged on distant voyages, and be equally at the service of the freshwater sailor, or finally be adapted to the important services so often required by our troops in the passage of torrents and rivers during a march through an unknown or hostile country.

The invention which is now offered to the public will, it is hoped, supply the lamentable deficiency which is above shown to exist; and, as the number of those who seek for food and employment in distant colonies is, owing to the constant and progressive increase in the population, yearly multiplying in numbers,

Fig. 2.

339

it becomes a matter of the highest importance to provide additional means for their safe passage across the ocean, or, at all events, for their temporary safety, in case of accident to the vessel which conveys them. The great difficulty in the way of providing an adequate number of boats for the safety of crew and passengers, has hitherto been, as already intimated, the unwieldiness and bulkiness of the boats at present in use. There can, according to the present mode of constructing them, be no more boats carried in every merchantman than can accommodate from forty to sixty persons;

[merged small][merged small][merged small][subsumed][merged small][ocr errors][subsumed][subsumed][merged small][merged small][merged small][merged small][graphic]

and even this number would be with difficulty contained in them, not to speak of the room required for water and provisions. The number of passengers and crew on board of emigrant ships is frequently double that above mentioned; and hence, in cases of shipwreck, foundering, or other casualties incidental to sea-voyages, there is always a prospect of those horrible struggles for preservation amongst the unhappy sufferers which have been before referred to.

The boat in question is of French in

vention, but has been patented in this country as well as in France. It is constructed upon the principle of a skeleton frame, easily put together, and as easily disconnected and folded in a small compass. The skeleton is constructed so as to fold easily and commodiously into onesixth of the space which it occupies when it is expanded and put to its proper use as a boat; and it is covered over with two folds of canvass of the best and strongest quality, which, after having been previously prepared with dissolved

caoutchouc, are glued one to the other, on the inner side of each, by a solution of the same material, so as to form an impenetrable and durable covering, wholly impervious to water, and more capable of resisting a sudden shock from breakers or sunken rocks, than either oak or the strongest deal planks would be. To provide for the permanent and unconquerable buoyancy of the safety-boat, it is provided with air-cells, or cases partitioned off, and each rendered independent of the other, so that in case of an accidental fissure being made in any one of these cells, the remainder, being uninjured, enable the boat to preserve its buoyancy.

The strength of the canvass can be increased at pleasure, according to the size of the boat, or the mode in which it is to be employed, so as to give this material a degree of strength equal to that of sheet iron; while its pliability adds greatly to the safety of the boat, by enabling it to sustain the shock of an accidental encounter with a rock or other hard body, by which an ordinary boat would be staved and swamped. The interior of the boat may, moreover, be strengthened to any degree required by the employment of thin sheets of iron or planks of wood, disposed so as to form a commodious bulwark and footing along the sides and bottom.

Having thus sketched, in a cursory manner, the advantages and facilities which at the first aspect of the invention are suggested to the mind, it may be advisable to examine what has actually been achieved by the employment of boats constructed upon this principle, of the materials indicated, in the kingdom of France; and as these facts are on record as having taken place under the immediate cognisance of the Minister of Commerce, the Duke of Orleans, and various other persons of the highest rank and of the first intelligence in France, they, perhaps, will serve in some degree as an apology for what might be said of the capacities of this patent boat. In the Journal des Débáts of April 21, 1841, we find the following description of one of these boats:

"We have recently spoken of the new patent boats, which take to pieces, and are readily constructed, and which were lately exhibited in minature on the Seine.

"A trial of far greater importance was

made, of their powers of conveying merchandise, in the presence of the Minister of Commerce yesterday, which was also witnessed by a vast number of spectators.

"The first large sized boat of this description reached Paris from Auxerre after a passage of unusual rapidity, and equal freedom from accidents of every description. Notwithstanding many severe concussions to which the boat was purposely subjected during the passage,-notwithstanding, also, the lack of water, which delayed the passage of other boats on the river; and many other drawbacks, as well studied as accidental,-not the slightest injury was sustained by the boat, which preserved its form, as well as the solidity of its frame, most perfectly; nor was there the smallest leakage to be perceived. When it is stated that the boat was of the following dimensions, it will at once be perceived that the principle upon which it is proposed to construct them has been subjected to the severest test which could be devised, and that it has endured it with success :-The length of the boat was 32 metres, 25 centimetres; the breadth was 5 metres, 10 centimetres. The cargo, brought from Auxerre, (in the centre of Burgundy,) consisted of 17 decasteres of new wood, weighing 89,862 kilos, (80 tons, 5 cwt.;) 4,000 metres of wood in planks, weighing 1,8000 kilos, (16 tons, 1 cwt. ;) and several hogsheads of wine, weighing 2,138 kilos, (2 tons,) making altogether 110,000 kilos (98 tons, 6 cwt.) of cargo, which was safely delivered at the Quai d'Orsay. As soon as the cargo was discharged, the boat was taken to pieces, (which was effected in three or four minutes' time,) and being placed on two carts, the materials were conveyed to Auxerre, to be again put together, and floated down the stream with another cargo. This experiment, therefore, amply testifies to the strength and powers of resistance of the materials of which these boats are constructed; and as their facility of setting up and taking to pieces depends wholly upon their size, it will be found that five minutes, upon an average, will suffice to ship or unship a boat large enough to carry with ease and safety from twenty to forty persons."

In a mere preliminary sketch such as this, it is unnecessary to expatiate upon the numberless ways in which this invention may be turned to account. It offers to those who are fond of aquatic pleasures a safe and inexpensive means of pursuing their amusements: a folding boat, constructed upon the principle herein described, may be carried by one man to the water's edge, expanded and fitted out in a few minutes' time, and

« ZurückWeiter »