MR. GOSLING'S IMPROVEMENT UPON THE ARMSTRONG GUN, &c.

BESSEMER'S IMPROVED FURNACE FOR THE MANUFACTURE OF IRON AND STEEL.

WRIGHT'S METHOD OF PREVENTING
BOILER EXPLOSIONS.

MR. E. T. WRIGHT, Engineer, of Wolverhampton,
has just patented the method of preventing boiler
explosions by connecting a water buoy or float in
the steam boiler with the furnace door, or with a
door opening into the furnace, so that when the
water in the boiler falls below a given level the
door is opened, and cold air is admitted into the
furnace, "whereby the boiler is cooled, and the
draught through the fire to a great extent sus-
pended; the overheating and consequent danger
of explosion of the boiler is thereby prevented,
and the attendant on proceeding to fire is warned
of the state of the water in the boiler by the open
door." The inventor sometimes connects the float
FICI

FIC.2

in the boiler with the furnace-door by means of a chain and pulley, as illustrated in the engravings, Figs. 1 and 2; e is the float hung to the lever f in the boiler. The said lever f turns upon a fulcrum at 9; a chain h passing over the pulley i connects the float e with the furnace-door k. By the descent of the float e the furnace-door k is raised. In boilers of the kind represented the distance between the water level and the furnace flue is sometimes insufficient to allow of the descent of the float through the requisite distance when the said float is immediately over the said flue. On this account the float is placed on one side as shown.

ON TIMBER FOR SHIP - BUILDING.
BY LEONARD WRAY.

FROM time to time during my life I have had a great
deal to do with a number of the principal timber
woods of Europe, Asia, Africa, and America, which
are known and classed by the timber-merchants and
ship-builders of Europe; and I may moreover say,
that I am very fairly acquainted with several timber
woods which are almost wholly unknown in this
country. With such a knowledge of these timbers, I
have long been struck with the fact that, when used
in the construction of ships, their accredited durability
seems woefully at variance with that which we find
possessed by the same descriptions of woods when they
are used in various ways on shore. Timber which has
the reputation of remaining perfectly sound for a
hundred years and more in various structures, such as
noblemen's mansions, churches, cathedrals, &c., when,
for the purpose of ship-building, it is brought under
the rigid classification of "Lloyd's!" is classed no
higher, in any case, than thirteen years (in the first

* From the paper read at the Society of Arts on May 3rd.

likewise their differences, both of kind and locality, but they are by no means of so important a nature as

to demand the same marked notice as I have taken in

instance), even with all the well-defined advantages of
copper fastening and other requirements indis-
pensable in a firstclass ship! True, this term may
be renewed for a further period of five years by respect to the varieties of teak. These eight des-
effecting a genuine and complete "restoration!"criptions of timber hold, then, a very high and de-
but this is in general so troublesome and served character from Lloyd's classification, for with
expensive a course, that in nine cases out of ten either of them may a first-class ship be built without
the owner had better build an entirely new vessel the admixture of any other wood. But upwards of
than have recourse to it. A ship being once off twenty other kinds of timber are permitted to be used
the first letter at Lloyd's, very rapidly runs down in certain specified portions of a first-class ship; and
the scale of her classification, unless kept up to some of these, at least, are no doubt working them-
a certain letter by constant surveys and expensive selves up into a place amongst the highest-class
repairs; but through these I do not purpose following woods. At first sight it may appear somewhat harsh,
her. We have had instances, and those tolerably and even unreasonable, to place such a magnificent
numerous, of ships, constructed of teak, mahogany, timber as the mahogany in the category of second-
and even oak, lasting for a very long series of years, and rate woods, the more so as we have had many well-
being comparatively sound in their timbers when authenticated instances of the extraordinary strength
wrecked or broken up. On the other hand, cases are and durability of ships built almost entirely of ma-
by no means rare of vessels, built even in the Govern-hogany; amongst which I may mention the oft-quoted
ment dock-yards, being-so to speak-unsound from case of the Spanish 80-gun ship named Gibraltar, cap-
the day they first entered the water. Indeed, we tured by the English in 1757, and broken up at the age
can recal instances, and might give the names of of 100 years, when all her timbers were found to be per-
men-of-war which were said to be thoroughly rotton fectly sound. But we must, in relation to these par-
before they were ever launched. These speaking facts ticular cases, bear in mind two circumstances which
may well arrest our attention, and demand an earnest are in themselves all-important, viz., that in the first
unprejudiced investigation.
place, only the choicest and most superior description
of mahogany was employed by the Spanish Govern-
ment in the construction of the Gibraltar (which was
built at the Havannah), and that no expense what-
ever was spared in the selection. Secondly, that such
a selection of choice mahogany for the entire con-
struction of a merchant ship at the present day
would be far too expensive to suit even our princely
ship-owners; whilst I need scarcely add that "swamp
mahogany," or, indeed, any of inferior quality, would
be highly unsafe, and, consequently, inadmissible for
the timbering" of a ship, however far it might be
allowed for "inside" and "outside planking," &c.
What the Crown of Spain so wisely did in days of
yore has been, in my estimation, wisely imitated but
a few years since by our own Government in the case
of the Queen's beautiful steam-yacht the Victoria and
Albert, which is, I believe, almost wholly constructed of
choice mahogany, and may, with ordinary care, con-
tinue in existence long enough to carry in pleasure
and safety her Majesty's great-great-grandchildren.

No sane man will, for a moment, call in question the justice or wisdom of those rules established by Lloyd's for the building and classification of ships. But I neverthless feel convinced that any useful and judicious experiments, tried by individuals, would always be fairly viewed and fairly encouraged by Lloyd's.

In ships of war, it is evidently extremely desirable to attain the highest possible range of durability; for in the peculiar circumstances of ships built for the Crown and of those built for the merchant service, there is this wide difference, that the former know not Lloyd's or its underwriters, whereas, the latter must "live, move, and have their being" according to Lloyd's, or that great body would certainly not know them or insure them. Mahogany of hard texture" is, however, so far admitted in the construction of A 1 ships as to include beams and hooks, planking to light mark, and the whole of the inside knees, rudder, and windlass, main pieces, outside planking. As there is a pretty general misconception observe that "superior northern Honduras is as in respect to the specific gravity of this wood, I may heavy as Travancore teak, and even heavier than Malabar teak

TIMBERS USED IN SHIP-BUILDING. According to Lloyd's classification of timbers, we find that first-class comprises only the following:The English and the African oak, the live oak of America, the mora and greenheart of Guiana, the teak and saul of India, and the iron-bark of Australia --being eight in all-of which number America supplies three; India two; and Europe, Africa, and Australia, only one each. These timbers are all close: grained and compact; hard, strong, heavy, and durable, being more or less naturally impregnated with certain oily, resinous, or astringent matters. The oaks (containing an acid and an astringent principle) are indubitably more liable to "rot" than the other named woods which abound in oily or resinous matter; hence we find ships built of the best English oak destroyed very speedily by "dry rot." I do not, however, say that even a wood so abounding in oil as the teak does not occasionally exhibit "decay;" on the contrary, experience has shown that this timber sometimes exhibits decay to an unexpected degreee. On this point, however, I must beg of you to remark, that the varieties of teak are numerous, and that the by the peculiarities of climate, soil, and seasons in character of the wood is very materially influenced the locality from which it is obtained. Thus, we have the finest description of teak from Malabar; that from Travancore, from Ceylon, from Java, from the Malayan Peninsula, from the Burmese territories, and from the Tenassarim provinces. Of all these the Burmese and Tenassarim varieties are held to be the most inferior, simply because the great proportion of that shipped both at Rangoon and at Maulmain is timber grown on the rich, low, alluvial soils formed by the great rivers on whose waters they are eventu ally floated to market. In justice, however, to these ports of supply, I must state the fact that, both in As may well be supposed, the cost of first-class Burmah and Tenassarim, the quality of teak, as a woods is high, and the supply is not at all times matter of course, varies according to the locality and equal to the demand. It is desirable, therefore, to soil on which it is grown. And we may therefore know how the supply can be largely increased, and very fairly class the timber obtained from them as the cost considerably diminished. But previously to being good, better, and best. We find teak grown entering on that part of my subject, I must not omit. on high, dry, and open land, of a fine quality, being to notice the silent but rapid revolution which is closer and more compact, and abounding in a mild, taking place in ship-building for the merchant serbland oil, which scarcely affects the iron bolts that vice. This is not only in the increased and increasing promay be driven into it. Whereas that grown in the portion of iron used in the bracing, strengthening, and dense forests of the wet, low-lying alluvials, is lighter, general framework of ships, but in the decided prefercoarser grained, and contains an acrid oil, which not ence which even the most cautious men are gradually only affects iron very materially, but even, to a certain showing for ships built wholly of iron! Ships have extent, poisons and inflames the hand which has been been built comprising full fifty per cent. of iron, but pierced by its splinters. We find also the weight and such half-measures do not seem to satisfy the minds consequent specific gravity of teak varying in a most of men now. The great cause of "iron versus wood" remarkable manner, viz., from a minimum of 583 to a is not, however, yet gained; the triumph may still be maximum of 1056 (according to the experiments by long in coming! The disastrous influence of iron Mr. Seppings;) although for all practical purposes we upon the compasses-the treacherous character of may take the range to be from 600 to 750. You are iron plates and iron rivets-the pertinacious par all, of course, aware that differences in situation and tiality of barnacles for iron bottoms-all these still soil create corresponding differences in oak, in elm, exercise great influence upon many minds; but last, and in all other English timber woods; but because and above all, it is not the habit of our sturdy, sureteak happens to have its habitat in the "nethermost going countrymen to make any great change in a parts of the earth," this simple law of nature seems hurry. I do not hesitate to declare my own full belief to be overlooked by all save by those few who have that the compasses will traverse correctly-that both made these subjects their especial study. The green-plates and rivets will prove steadfast, firm, and heart, the mora, the saul, and the iron-bark, have faithful; and even that the "barnacles" may be

or English oak; the inferior qualities of mahogany alone being so very light and buoyant. I should be very pleased to see good mahogany enter more largely than it now does into the construction of ships; but I am persuaded that its judgment and discrimination." more extended employment must be regulated with

see

effectually kept off!-yet, I should not wish to so great a change progress otherwise than calmly, carefully, and safely;-which it can only do under the guidance of further experience and the practical success of many years. As I have expressed my belief in the undeniable suitability of iron ships for mercantile pursuits, I must, at the same time, state my opinion against them, if applied to warlike purposes. Next to the entire non-existence of a navy, I can conceive nothing so perilous to the interest and safety of this country, as having our ships of war constructed of iron! Nor can I, at present, conceive how the inventive faculties of manaided by all the science of the age-can afford any adequate safeguard against the disastrous liabilities of a thin iron structure, such as a ship exposed on the ocean to the terrible effects of a cannonade! It is quite probable, and indeed almost essential, that the partial use of iron in the construction of men-of-war should be very largely extended, as it would add considerably to their strength, lightness, and internal dimensions; but notwitstanding this increased and increasing employment of iron, I do not see any likelihood of the demand for ship-building timber abating for many years to come; on the contrary, I fancy that I can distinctly foresee a very enormous increase for the purposes of our navy alone; not merely for the contemplated addition and conversion of our war-ships, but for the continual building of new ones, to replace those which are now being converted into screw steamers. I hold it, as the inevitable result of such conversion, that dry-rot will make swift havoc amongst them, unless the only preventive measures possible have been timely effected; but as I shall have to refer to this important point again, we will now return to the more immediate matter from which I digressed.

for trucking. Such gangs are usually provided with from 6 to 10 ponderous trucks, having 14 oxen to each truck; and as these work only at night, by torch light, we can readily imagine how carefully the roads must be cleared of all obstacles. When the rains set in, and their logs are floating down towards the coast, these hardy fellows follow each batch in their little pitpans, and exercise all their amphibious dexterity in securing the safe and unimpeded passage of their property. Now, I have not given you this slight sketch for the purpose of mere amusement, but because I wish in the most emphatic manner to point out the important fact that, in this colony of Honduras, we have the largest and most practical body of tropical lumberers that exist on the face of the earth. That there is now exported from that colony about 25,000 tons of mahogany and about 6,000 tons of logwood per annum. That these woodsmen, in the pursuit of these two staple products, continually pass and repass vast quantities of fine and valuable timbers, in every way suitable for ship-building. The forests in which they live and work contain some of the finest quality timber in the world, and that in extraordinary profusion. I do not pretend to know many of these woods, but the following I am well acquainted with the greenheart, the live oak (Bignonia), and other oaks; the mahoe, the bullet tree, the Neesberry bullet tree, the iron-wood, the locust (used for ships' planking and tree-nails), the dogwood, the red pine, the pitch pine (much superior to that of Carolina and the other Southern States of America), the cedar (Cedrela odorata), a light and durable wood, not liable to dry rot nor subject to the attack of insects. The trunk of this tree is 70 to 80 feet long, with a diameter of from 4 to 7 feet. I am sure I need not dwell upon the great value of these fine timber woods, but I must again observe that INCREASED SUPPLIES OF SHIP-BUILDING TIMBER. there are numerous others, perhaps equally valuable, It is not sufficient that we discover forests of timber, which I cannot now enumerate. It is quite clear to even of the finest quality; for before they can be my mind that the Honduras woodsmen could realise a very great deal more money, and with infinitely less turned to profitable account, we require a pupulation to fell and trim the timber, a good shipping port, and labour, by preparing for market these timbers than the cheapest possible means of bringing the timber they now do from their mahogany and logwood; but as the gangs are always hired under contract by some from its native forests down to the port of shipment. merchant or mercantile firm in Belize, it is evident But we require even more than this, in the majority of that the initiative must be taken by those entercases, viz., a climate such as the European Superin-prising gentlemen. The safest course, perhaps, would tendents can not only exist in, but be able to expose be to commence the attempt by combining the two themselves in with some degree of impunity. As a summary, then, we may consider to be essential: 1. A objects, for the same roads necessary for the trucking tolerable climate; 2. abundance of good timber; 3. A of mahogany would serve for the transport of the other timbers selected. There is a distinguished sufficient amount of cheap labour; 4. Numerous inter- member of this society, Chief Justice Temple, still secting creeks and rivers to float down the timbers; residing in Honduras, to whom we are all indebted and lastly, a safe and eligible port for their shipment. for the indefatigable exertions he has made to attract It is quite in vain for visionaries or enthusiasts to call attention to the capabilities and resources of this fine attention to vast forests of stately timber, existing in colony, and I am sure that his advice in relation to regions where these essentials are not co-existing; for the course I have just suggested would be particularly every man who has had any experience in such matters knows full well the numerous difficulties that beset the labours of timber-cutting gangs. Leaving, then, all the beautiful and undoubtedly valuable woods which have their habitat in impracticable and impossible localities, I shall bring before you those that are easy of access, and that may be transported with facility to eligible seaports. Confining myself to those woods which are, or which may yet become first class on Lloyd's books, I will first present to your notice the extraordinary capabilities of Honduras.

Even before the time of the celebrated Dampier, the cutting of logwood and mahogany had become an important business in that colony. More than 180 years have since elapsed, and still it is almost wholly known to the world for its large exports of mahogany and logwood, and for these only! During this long series of years, Honduras has had its organised bands of wood-cutters, whose peculiar occupation has descended from father to son through so many generations, that it has become a part and parcel of their very natures. From childhood to the grave, the sole business of their lives is hunting for and cutting timber in the dry season; floating it down to Belize during the rains; and enlivening that seething town with their fantastic dances and drunken revels, until their money being exhausted, they once more are obliged to betake themselves to their occupation in the dense forest. Hard and laborious indeed is their life in the bush; the felling and squaring up of the vast logs of mahogany being really the lightest portion of their task; for they have to clear away the thick and thorny underwood, cut down and remove thousands of immense trees, in order to form roads, whereon their trucks can pass with their heavy loads to some creek or river. These main and bye-roads are often miles in length, all carefully graded and rendered complete by numerous temporary bridges strongly constructed. To make these roads and bridges, a party of 50 to 60 men are detached, whilst the remaining number are preparing the mahogany

valuable and instructive.

(To be continued in our next.)

THE ATLANTIC PAYING-OUT MACHINERY.

TO THE EDITORS OF THE "MECHANICS' MAGAZINE."

GENTLEMEN,-I see in your impression of April 29,
under the head of "Weekly Gossip," an abstract of
a "report of a select committee of the American In-
stitute of New York, appointed (by whom?) to
examine the paying-out machinery on board of the
U.S. frigate Niagara, and to furnish a report thereon
concerning the design and construction thereof." We
are pretty well accustomed in this country to pass
over brother Jonathan's cormorant propensities with-
out notice; but in this instance the exparte decision
of this mock committee (who have certainly gone the
entire ticket) upon work done in this country, is so
glaring in its injustice to those who have borne the
burden and heat of the day, that it would not be right
to allow the statement which your columns have dis-
seminated through the country to pass uncontradicted.
The object of the meeting of the committee has mani-
festly been to show that Mr. W. E. Everett, of the
U.S. navy, who had charge of the engines of the
Niagara on her first trip, was the sole inventor and
designer of the machinery used for paying-out the
Atlantic cable in July and August, 1858. For my
own part, I cannot accept this machine as altogether
the best for the purpose (indeed, it is clear that it was
too heavy for use in very rough weather, since men
were employed on board the Agamemnon to keep the
wheels moving during the rough weather which she
encountered, when her stern dropped so much as to
withdraw the strain from the cable), but some parts
of it were new, and a great advance upon any ma-
chinery of the kind employed before. I believe the
facts of the case are as follows:-The original ma-
chinery consisted of two machines, either of which
could be used for paying-out or for hauling in; one of

these had four sheaves, the other two. The "commission of engineers" (Mr. Everett being one of the commission) advised in September, 1857, that certain alterations should be made in the machinery, the bulk of which had been recommended to them by Mr. (now Sir Charles) Bright, the engineer, and one of the original projecters of the Atlantic line. One of their most important recommendations was the use of a form of brake invented by Mr. J. G. Appold, F.R.S., which has been employed for testing the engines of the Royal Agricultural Society for a long time, and which afforded a certain degree of compen sation to any inequality of strain. If I am not mistaken, the first suggestion of this brake emanated from Mr. Appold himself, and was concurred in by the committee. The brake used by the Agricultural Society was set up by Mr. Amos at the Gutta Percha Company's works in the City-road, at the request of the Atlantic Company's engineer, and (after some experiments) was determined upon; at this time Mr. Everett was not even in England. No alteration whatever was made in the principle of the brakes finally used, and scarcely any in the details of construction; certainly none of the slightest importance. The machines with two over-hanging sheaves used in the former expedition were fitted with Mr. Appold's brakes at the works of Messrs. Easton and Amos. The chief parts of the machines were adopted without any change, but new sheaves were made with deeper grooves, in accordance with Sir Charles Bright's advice, and his recommendation as to guards to prevent the cable from escaping out of the grooves, scrapers to clean the grooves from the accumulation of tar and other details were carried into effect. As to the new parts of the machine-the dynamometer for indicating the strain, and the hand-wheel for removing all pressure immediately, if required—the former was patented by Sir Charles Bright in the previous year, and the latter was proposed by Mr. Amos, who took the greatest interest in the construction of the machinery from first to last, and the initiative in the practical design and carrying out of the wishes of Sir C. Bright, the engineer of the company, Messrs. Penn, Lloyd, and Field, who were good enough to lend their valuable aid to the company in the matter, and Mr. Everett, to whom was confided the experiments upon the materials and lubrication of the brakes recommended by the engineer of the company in September, 1857, and the supervision of the construction of the Niagara's machinery, Mr. Clifford being charged with the superintendence of that for the Agamemnon. Mr. Canning and Mr. Woodhouse, to whom was entrusted the important duty of coiling the cable on board the ships, were also consulted as to the machinery, and I shall be very much surprised if Mr. Everett ventures forth from the cover of this self-appointed committee to say that he designed any part of the machinery in question, or even suggested a single bolt or screw in it.

The fact is, that brother Jonathan has intended to be quite smart about the cable business; and no greater example can be found of English frankness and straightforwardness, as compared with American jealousy and unfairness, than the generous manner in which the engineer-in-chief of the Atlantic Company spoke of his American co-adjutors in his published report, as well as in his speech at the banquet given to him at Dublin, and the omission of all allusion to him in the celebration on the other side when all America went mad about the submersion of the cable

in her eagerness to claim the entire thing as her own. I need not remind you of the smallness of the share which Americans really had in the undertaking. Three of the original promoters of the company, Sir Charles Bright, Mr. Brett, and Mr. Whitehouse were Englishmen, one only (Mr. Cyrus Field) being an American. More than three-fourths of the capital was found by British subscriptions; and out of the ships furnished by the two Governments to carry out the enterprise last year, the Agamemnon, the Valorous, the Gorgan, and the Porcupine, were provided by our Government, while the United States Government produced only the Niagara.

Under these circumstances it would be well for our Yankee friends to adopt a rule in the celebrated game of poker, to which they are so attached, viz., never to brag without holding a good hand.-I am, gentle men, your obedient servant, T. B. M.

GENTLEMEN,-Under the above head a very strong THE LIGHT - DRAUGHT STEAMERS FOR willing to rely on the authority of the MECHANICS'