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most efficient propeller is passed over as gets that he had just before shown, by a thing of no regard !

the Bristol experiments, that a stern Not, however, be it confessed, without somewhat square is the very best form for more than a due share of the “soft saw a screw propeller. der.” “For, after all," quoth Mr. Gal Captain Carpenter, as our readers are loway, "there is something extremely aware, employs two propellers, consisting pleasing in these modifications, which of fat blades of a trapezoidal form, will secure admiration for their refined placed in the after quarter of the vessel. elegance and ingenuity, WHATEVER MAY 1. The chief defect” which Mr. Gallo.

ULTIMATE EFFICIENCY." way finds with this arrangement is, "the Faugh! Why does he not say, at once, making the blades plain surfaces, inwhat he thinks, which is, manifestly, stead of sections of screws; the result that they are all fudge ? Has he any will either be excessive displacement at notion how much he insults the objects of the outer portions, or in direct opposition his fulsome adulation, by supposing that to the vessel's progress at the parts near they can take any pride in elegance the centre.” or“ ingenuity," which has not ultimate Mr. Galloway's "own" plan is thus efficiency” for its sole end and object ? described. “Hunt's Propeller" is the next which

“The parts of the screw near the centre comes under Mr. Galloway's killing kind expend the greatest portion of their effort

Here he quite omits to state, that in turning the water round without aiding the inventor sets no store whatever on considerably in the populsion of the vessel. the form of his propeller, (See Mech. The object of several of the inventions we Mag., No. 880, for June 20, 1840) and he have described has partly been to obviate mentions, incidentally only, what is, in

this defect. The evil may be in a great defact, the sole distinguishing feature of this

gree remedied without departing considerably very clever invention, namely the combi

from the form of the screw of the Archi.

medes. To demonstrate this, let us suppose nation of the propeller and rudder in one. “ Blaxland's Propeller" fares still

the inner portion of that screw to be reworse. It is said to " resolve itself into

moved, and the outer part to be merely at

tached by arms radiating from the axis to the a method of making the screw by sub

leading and after end of the screw, and that stituting circular blades for the triangular

to the leading arms a number of cords or plates described and shown as the mode

flexible lines be affixed. Under such cir. of constructing the screw of the Archi

cumstances, if the screw be made to propel medes ;” and yet we are told, that “it a vessel at its maximum velocity, these cords must necessarily be inferior in effect to or flexible lines will generate helices in their the screw of the Archimedes "- that is, progress through the water. The pitch of inferior to what it is said to resolve itself in these helices, however, will be less than the to! Neither is any notice whatever taken, pitch of the screw, inasmuch as they will (except in the way of literal description,)

coincide with the actual motion of the vessel, of what undoubtedly forms the best fea

while the screw has a pitch equal to the ves. ture of the Blaxland Propeller—the mode

sel's motion in addition to its own slip. in which the power of the engine is com

“If, therefore, we could construct the part

of the screw nearest the centre in the form municated by bands to the screw-shaft.

of the helices thus generated, we might make Mr. David Napier's plan consists in

the screw with threads continued from the placing two wheels, only partially im

axis to the periphery, but without diagonal mersed, at the stern of the vessel, one a

loss near the centre; and to approximate to little in advance of the other, so that the this as much as possible, the writer proposes blades of one just clear the axis of the to decrease the pitch from the periphery to other. “ An iron steam-vessel,” says the axis, so as to make the parts near the Mr. Galloway, “has been constructed by middle coincide with the vessel's motion. Mr. Napier, for carrying this contrivance We consider its chief value to consist in its into effect, which, though obviously de enabling us to attach the screw to the aris fective in form, (her after end terminat the whole of its length, as in the case in the ing nearly in a square, and the pro

screw of the Archimedes, but without the pellers, consequently, consuming a large

same loss of power."-p. 62. portion of their power in the dead water As regards all that part of the precedthus produced,) has attained a speed of ing plan which consists in removing the 11 miles per hour.” Mr. Galloway for inner portion of the screw, Mr. Galloway

or

has been anticipated by Mr. John C. In one way or other there is now a Haddan, who patented, 22nd January, certainty of the question as to the real 1839, a plan for propelling vessels, of value of the Archimedean propeller being which this was the distinguishing cha very speedily set at rest. It appears from racteristic. “I claim,” says Mr. Had the following paragraph that independan, in his specification, “as my inven dently of the Bee, there are at the pretion the forming and using of screw's sertt time no less than six vessels of firstwith openings or spaces in their threads." rate magnitude, either just completed, or

Mr. Galloway's supplementary list fitting out on this plan might have included several other varie.

“ The ultimate fate of these methods of ties of sub-marine propellers, as Wood

populsion is now beyond the influence either croft's, Hale's, &c.; but seeing that all

of praise or depreciation. Four vessels are those he has described, with the single already in operation, fitted under the patent exception of the Archimedean, of Mr. Smith, and the Great Britain,' now Smith's, are only shown up in order to building at Bristol, is to be propelled with be dismissed on most frivolous and in the screw driven by engines of 1000 horses' sufficient grounds, it is scarcely to be re power. A vessel of 1500 tons is also just gretted that his collection is not more completed at Londonderry, which is to be extensive.

propelled in the same way. The British Mr. Galloway closes his treatise with

Government are fitting the Rattler, which is an account of some experiments made

of 800 tons burden, and has engines of 200 with the Government steamer Bee, to

horses' power, to prove the power of the test the capabilities of the screw, which

screw by competing with the Polyphemus,

which is of the like power and tonnage; and appear to have come to his knowledge

the French Government are fitting three veswhen just on the eve of publication, (for sels to be impelled by the same agency. they were made only on the 20th, 21st, Messrs. Rennie and others are also about and 23rd of June last,) and which he ad carrying out their plans on a large scale. mits square but indifferently with the The rapid strides which the system has made favourable opinions expressed in the in the space of two years, before which it preceding part of the work.

was almost universally unpopular, are the sults," he says,

were certainly more best evidence of its importance ; and there unfavourable to the screw than either can be no doubt that if the machinery for the experiments with the Archimedes or communicating motion from the engine to our calculations would lead us to expect.”

the screw can be rendered simple and dur. The Bee was fitted up expressly for the

able, this method of propelling will become purpose of ascertaining, by a sort of ex

useful as an auxiliary power, and in certain periment which would be free from every

classes of war steamers, even if it should not

be found equal to paddle wheels under all objection, what the real power of the

circumstances."'--p. 67. screw was ; and accordingly the chinery was so arranged as to propel her So far as the experiments already either by paddle-wheels or the screw of made—which have been both very nuMr. Smith.” This we consider even a merous and conducted generally under better test than that of employing “two

most favourable circumstances

- may vessels of the same form and power,' justify us in coming to a conclusion, we such as the Rattler and Polyphemus, should say that there is no likelihood that the one fitted with the screw, and the the Archimedean propeller will ever be other with paddle-wheels; for it is well able to compete in point of speed with known that the same lines and same the paddle-wheel, whatever may be the weights do not always in sea affairs pro advantages which it possesses in point of duce identical results. Fifteen trials position. made with the screw applied to the Bee, How the case may be, if Ericsson's gave an average speed of only 7-358 miles. propeller, or any of the others proposed Mr. Galloway tells us that “Mr. Smith is adopted, we have not as yet the attributes this result to the screw being means of judging. Ericsson's plan, too small," and that it may be perfectly though neglected in this country, ascertained whether this is the cause of appears to be making great way in Amethe inferior results obtained with the rica. Besides the Robert Stockton, Bee or not, the Admiralty have ordered of which we have before spoken, and a larger "one to be substituted. the Clarion, which was lost on the coast

" The re

ma

of Florida, there have been six other if frd of this profit, viz., £6. 18. 8td., American vessels fitted with Captain go to the proprietary, the profits of Ericsson's double wheels-two which each surviving subscriber will only be ply on Lakes Ontario and Erie, passing £12. 38. 58d. In this case, instead of through the Welland canal, and four (of £100, each living subscriber will only be iron) which trade between Philadelphia entitled to (100— }rd of 18-26) £93-913 ; and New York. A newspaper account. hence, by proportion, 93.913 : 100 : : of two of the latter will be found among 5:339 : 5.685 = £5. 138. & d. That is, the Notes and Notices of our present the annual premium will be £5. 138. 8}d., Number.

and 81.74 + jrd of 18-26 87.827, and Although Mr. Galloway has by no 87.827 • 1:806111 = 48 622 = £48. 128. means treated his subject in a way to be 5 d. the single premium. generally commended, it is not to be de By a like process, when the rate of innied that he has collected together a terest is 4 per cent., the annual premium great deal of most valuable information will be £4 178.91d., and the single preupon it. It may be even admitted that mium £40. 1s. 94d. The like premiums he has, by his mathematical, or quasi- by the Northampton Table will be £5. mathematical investigations, advanced to 55. 0fd, and £4. 9s. 24d. ; the single some extent our knowledge of its scien premiums being £44. 08. 10d., and £36. tific principles. But to qualify a person 6s. lad. to wear, with any credit to himself or his There is a curious circumstance reemployers, the mantle of a Tredgold, specting the waste of human life deduced he must possess something more than

from the Northampton and Swiss Tables mere industry and a mere smattering of of mortality. Thus, between the ages of learning; he should be able to sound the 23 and 43 the mortality of 100 persons depths as well as the shallows of science

by the Northampton Table is 31; and by -have eyes to see the both sides which the Swiss Table, for the same ages and every question has, and the courage and number of persons and period of time, honesty to pronounce which in his judg the deaths are only 18; and these numment is the right.

bers are in the proportion of 7 to 4 (al.-most exactly). Now contrast this with the following extract from Mr. Morgan, vol. ii. page 443.

“During 33 years, from January 1768, to January 1801, the number of assurances

(in the Equitable) on single lives had been Sir,-- We have calculated from the 83,201, of which number 60,597 were on the Northampton Table, where the rate of lives of persons under 50 years of age, among interest is 3 per cent., that the annual

whom the deaths were fewer than those in premium is £ 4. 138. 51d., or the whole

the Northampton Table in the proportion in one premium £38. 78. & d., and that

of 4 to 7." when the interest is 4 per cent., the

And now, Mr. Editor, having answered, like premiums, are £t. 08. 14d., and as well as I can, the conditions required £31. 12s. 93d. The annual premiums by your correspondent, Iver McIver, I when the rate of interest is 3 and 4 per shall only in conclusion add, that if any cent., by the Swiss Table are £5.68.9 d., Assurance Company were to adopt the and £t. Ils. 74d. The single premiums scheme mentioned by Iver McIver, and being £15. 58. 14d., and £37. 6s. 1d. to calculate their premiums from the

Supposing the proprietary of such a Northampton Tables, their loss would le scheme are to have įrd of the profits most certain, unless they wished to play arising from deaths, but that the living the same kind of game as the Western subscribers are still to receive £100 each Assurance Company did about two or at the expiration of 20 years, it is required

three years ago. to determine what the annual and single I am, Mr. Editor, yours, &c., premiums will be on this supposition ? Ist, By the Swiss Table, when the

GEORGE Scott. interest is 3 per cent.

Cochrane Terrace, St. John's Wood. Each living subscriber will have a profit of (100-01:74) £18. 5s. 24d. ; but,

THE

CASE IN LIFE ASSURANCE-MR.

SCOTT IN CONCLUSION.

THE EXPLOSIVE BALL.

PERCUSSION SHELLS. Sir,- In the Jersey News of the 6th the exploded tube is renewable for a inst., is a rather designedly obscure, yet penny at each operation. T. H. P: pompous, announcement, extracted from

Extract from the American Paper rean American Paper, of a most wonder

ferred to by Mr. Pasley. ful discovery, effected in America, of a shot which explodes without a fuse the instant it strikes its mark, and which is

We, this day, by the politeness of Mr. W. said to be the most destructive weapon

F. Ketchum, of Buffalo, had the pleasure of

witnessing an experiment of his newly-inof war ever invented. Now, sir, if you

vented explosive ball. Mr. Ketchum made will please to refer to your own publica: six shots-(for the want of a proper target,) tion of the year 1823, No. 29, Novem -at trees, on the lake beach, from a sixber 14, p. 217, you will find it there re

pound brass gun, belonging to the Buffalo corded, that the invention is not that of Artillery. an American, but mine : that it is not a The ball is intended to explode on enterpresent day discovery, but of nineteen ing the object assailed to a desirable depth. years standing in the pages of the Lon The result of five of the shots was agreeable don Mechanics' Magazine, and there

to the inventor's design-entering the object described as a percussion shell. There

and exploding—showing the destructive efit may be read how it was treated by the fect of such explosions, to admiration,—the Board of Ordnance at Woolwich when

one failing to meet his views, being fired at

a tree of about 20 inches in diameter, struck presented in the month of December, 1812, although subsequently proved at

so far from the centre as to glance off on an

angle of 32 to 45 degrees, so that it did not Leith, by Col. Miller, of the Royal Ar

explode from want of sufficient opposition tillery, to be of extraordinary power, and

to its projectile motion. therefore of the greatest utility in the ser Mr. Ketchum says the principle is applicvice. The Condemnatory Report, signed able to all sizes of ordnance, from 6lb. to by General Farrington, bears date 15th the largest used in the army or navy-and Jan., 1813. The discovery, if such, was the nature of the construction is such that made by me, thirty years before the there is perfect safety in handling the balls American announcement, and of which for the purpose of loading, stowing away, or brother Jonathan may not be ignorant; transporting from place to place. for that he and every designer, reads

The balls being ready for use before taken on your very valuable Magazine there can

the ground for the experiment, we could disbe no doubt.

cover none of the internal construction

but ascertained that no fuse was in any way Your inserting the American account and the foregoing exposé in your widely

attached—and that the explosion is the reextended Book of Knowiedge, will

sult of, impingement when the balls assail

an object. The peculiar formation of the ball, oblige all patent-right sufferers, as also

seems to cause it to take a very accurate Your obedient servant, T. H. Pasley. direction--as the shots were made with more Jersey, August 12, 1842.

precision than we ever before witnessed

and it appears to us that there is as much P.S.-If an air-tight iron plug or

accuracy in the direction of the ball as that piston in a tin tube, one fourth of shot from a cut or creased rifle. which tube contains gunpowder, insert From the result of the trial, we are of ed in a rock or the stump of a large opinion that the inventor has accomplished tree, when the plug is suddenly and one of the most important objects ever atforcibly driven down, the stone or stump

tained in the construction of warlike wea. will be shivered to pieces, with much pons, and we hope the projector will not fail less danger to the operator, and less

to meet the encouragement which untiring trouble, as to confining the powder by

genius so richly merits.

We also saw sand, than according to the customary

a hand-grenade of Mr.

Ketchum's invention, which he had designed mode of effecting explosion by a match

for use in naval actions to be thrown from rupe. The percussion stroke may be

the vessel in close action--from the deck or given by a weight, the suspending-rope

round top-or in case of boarding, to be to which is passed vertically over a pulley used for the defence of forts, when an enemy and continued horizontally to any suit

might attempt to take them by storm. able distance where the quarry-man The grenade is so constructed as to be of chooses to place himself. The plug and suitable size and shape to throw--will weigh rope remain for repeated services, and about one pound-but may be made to weigh

more or less, according to the place of its effect of both the explosive ball and hand contemplated use. The formation and prin grenade, we cheerfully ascribe to Mr. ciples are such, that is perfectly safe to Ketchum the honour and ability of having handle, stow away, or transport, as occasion invented and constructed two of the most may require—yet they are sure to explode formidable and destructive missiles of war when thrown, by coming in contact with ever exhibited to the world. any substance as hard as wood, or even by

JONATHAN H. FORD, striking a man, and numerous experiments

A. I. ALLEN, have proved its effects on explosion to be

F. D. SPALDING. extremely destructive.

Thus with the fullest confidence in the Buffalo, N.Y., June 15, 1842.

HOUGHTON'S LUBRICATOR.

S

A

B

(Registered pursuant to Act of Parliament by Messrs. Hornwood and Monkman, Proprietors.) The ingenious lubricator represented pressing on the top side of the piston it in the prefixed engraving is the invention closes the lower valve, and when on the of James Houghton, a working engineer under side, the atmosphere closes the top of Oldham. Messrs. Horwood and valve ; so that at each stroke the quantity Monkman, to whom he has disposed of of oil or tallow lodged in the space behis right to it, informs us that it is at tween the valves is diffused over the cytended with a saving of no less than three linder. The sieve S, which is inserted fourths of the oil or tallow ordinarily loosely in the cup, is intended to strain consumed, besides adding considerably and clear the oil or tallow of all imto the engine power, in consequence of purities. the nice adjustment of the quantity of oil The invention is obviously applicable or tallow supplied, to the wants of the to all descriptions of revolving or sliding machinery. The

operation of the surfaces, as well as steam-engine pistons; apparatus will be readily understood by a little change in the mode of connecting an inspection of the engraving. A and it, being all that can be at any time necesB are two valves connected by a spindle sary, 10 adapt it to any sort of machinery which works through a hole in the cen requiring regular and constant lubricatre of the cup C. When the steam is tion,

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