RESULT of supplying His Majesty's 77th Regt. of Foot with Clothing according to Admea. surements taken by the ANDROMETER.

The Andrometer may be seen and examined at the House of Mr. Donald Currie, 20, Regent street, London,

REMARKS ON SOME POINTS OF NAVAL ARCHITECTURE.

BY H. W. ALLARDYCE, BOMBAY ENgineers.

MR. EDITOR,-Having read some remarks made by Mr. Bland on the paper on Naval Architecture which I sent you, and which you were kind enough to insert in your Journal for September last; and thinking that he seems to request some explanation on one or two points, I take the liberty of sending you the following observations, which, if you think them deserving, you will perhaps insert in a subsequent number of your Journal.

In the paper I sent you, I remarked, that it had been practically established, that in dragging a long piece of wood with a tapering end through the water, the resistance was greatest when it was dragged with the tapering end first;" and on that account I proposed that the main section of a vessel should be well forward, mentioning one-third of the length of the vessel from the stern, as perhaps the most desirable situation for it. Upon this Mr. Bland observes, "That putting this and other forms to the test of experiment, I found a positive evil to arise in the tapering end being dragged first." Now, from this remark, I should have concluded that Mr. Bland was of the same opinion as myself, viz., that the greatest breadth should be well forward, and the vessel taper gradually off towards the stern, had he not gone on to remark, that in the experiment which he made with the two models, one of which, in the immersed part, was formed like a fish, the other as a semiparallelopiped, there appeared to be no difference in their resistances." Now, what I draw my conclusions from is some very accurate experiments of Chapman, the celebrated Swedish constructor, which were repeated six times without any sensible variation; and as they will also throw considerable light on Mr. Bland's proposed method of building a vessel with parallel sides and bow-shaped ends, I shall insert them here.

66

Let A, B, C, represent three bodies; A has its extreme breadth in the middle, B at 2-7ths its length, and C at 1-7th its length. The bodies were of equal weight, their length equal, each end of them being a parabolic cone, and only differing in the part where the common base of the cones was placed relative to the length. When a given weight A moves 74 feet in 25 seconds of time, B moves the same distance with the same weight, its obtuse end foremost, in 26 seconds of time; its acute end foremost, in 24 seconds. Here it is proper to observe that the rate of velocity is about two miles an hour. The same bodies were then moved with an increased weight, A completes the same distance of 74 feet in 14 seconds.

B

Obtuse end foremost, ditto, ditto, in | The same bodies are now given a greater 14 ditto.

16 1-half, ditto.

velocity, A completes the distance of 74 feet in 11 seconds.

Obtuse end foremost, ditto, in 10

B

1-half, ditto.

Acute end foremost, ditto, in 10 1-half

ditto.

Obtuse end foremost, ditto, in 10 1-half, ditto.

Here the rate of velocity is nearly 3 C Acute end foremost, ditto, in 13 1-half

miles an hour, where A and the ob

tuse angle B are equal.

ditto.

Here the velocity is nearly at the rate of 5 miles an hour, where the obtuse angles outstrip the acuter.

Mr. Bland says, "I had, however, several proofs of the superiority in stability in favour of the semiparallelopiped over the fish-shaped model, which was chiefly owing to the means afforded for placing the centre of gravity

much lower in the former than the latter." In this I perfectly agree with Mr. B., and if he will take the trouble to experiment a little farther, he will find the semiparallelopiped form, or that of a rectangular box, is not only superior in stability to the fish-shaped form, but also to every other, and is the one that will roll least in a heavy sea: but when we have said this we have mentioned all that can be said in favour of such a form; for stability not being the only requisite in the construction of a ship, a vessel possessing this in ever so eminent a degree, and deficient in the other requisite qualities, must of course be bad. Let us now examine the defects of this form.1st, From having a flat bottom and perpendicular sides, by not being sufficiently lively to yield to the sea when it runs high, every wave will make a clear breach over her, to the manifest destruction of boats, spare booms, and every article on deck that is not firmly lashed down. 2ndly, It is well known that heavy seas acquire such a momentum in their progressive movement, that meeting with resistance from the hull of a vessel, the shock they give is so powerful, as to make every timber in her vibrate; and we have known one of the arms of a seventy-four's bower anchor snapped off by one of those curling and topping waves. Now, if the effect of the waves upon a vessel whose form was considered sufficiently yielding to the motion of the waves, be such as to break such strong material as a bower-anchor, what must it be against wood-work, which has not even the advantages of a curved form to protect it, but on the other hand is of that form well known to be most in danger from the violent action of the waves. 3rdly, As a prompt obedience of a vessel to her helm depends chiefly on the form of the stern, if too full the vessel will not be under proper command, for the dead water will in this case extend farther than the width of the rudder, and consequently deprive it of its best force. Now, if such is the case when the vessel is only rather too full, what must it be when the sides are parallel? I should be inclined to think, that the rudder would be almost, if not entirely, useless. But although I am an advocate for avoiding all fullness below the line of flotation in the after body, yet immediately above it the quarter should spread out, in order to present a sufficient quantity of support when the ship rises forward to a sea. Neither should the run of the vessel be too sudden, but the greater the proportional length of a ship is to her breadth, I should place the main section proportionally farther forward, thus making the run more gradual, and at the same time greatly increasing the power of the rudder, as the centre of gravity will be necessarily farther forward, and thus give more length to the lever upon which the rudder acts. 4thly, With regard to her velocity, that will be very considerably retarded, for although her extremities should be bow-shaped, yet from her sides being parallel she will meet with very great resistance. This is clearly exemplified in an experiment of Mr. de Romna's. The model he used was one of a 74-gun ship, and was 14 feet long. At 19 inches draft of water it moved 75 feet in 16.5 seconds; at 14 inches draft it moved 75 feet in 13.6 seconds. To the after body was then affixed a prism, having for its base the midship bend, thus—

It was then moved with the same weight. At 19 inches draft it moved 75 feet in 22.48 seconds. At 14 inches draft it moved 75 feet in 19.2 seconds, thus clearly proving the retarding influence of the semiparallelopiped form of vessel. Taking, therefore, all the advantages of this plan, and comparing them with the disadvantages, I think, that unless Mr. Bland can alter the laws of nature, he must consent to give up this new method of ship-building. It now only remains to say a few words on the semicylindrical form. Mr. Bland is of opinion that the centre of lateral resistance moves gradually forward towards the main section, in proportion as the vessel heels. Now, this I admit, when the action of the wind is such as to depress the bow considerably, and thus alter the horizontal trim of the vessel; but Mr. B.'s semiparallelopiped, or semicylindrical form is liable to the same objection: this, however, I would endeavour to correct, by reducing the

after-sail of the vessel, or increasing those forward, and thus keep the vessel still in equilibrio. But when the action of the wind is such as to make the vessel's heel parallel to themselves, I cannot then agree with Mr. Bland, but must assert, that the centre of lateral resistance, in my opinion, does not change its place, and the harder the gale blows the greater will appear the advantages of the fish-shaped over the semicylindrical vessel. For let us take the main section of each form, then we shall have something like the annexed figure.

Commander Pearce, who has written very ably on the position of the metacentre, gives the following proof of the stability of the sharp vessel over the full. Let W R represent the surface of the water. In the circular body the half-breadth a m is the radius of the semicircle a b c, and in consequence of the direction of the vertical effort of the water intersecting the point m, this point is the metacentre, and the two areas hdn, hin are equal, and the distance dh is equal to the distance hi. In the sharp body represented by a obs c, the inclination has caused the outline bsc of one side of the bottom to become more vertical, while that on the other aob is more horizontal, causing the wide part of the former to emerge, while the widest part of the latter has become immersed; and the comparison exhibited of the two forms shews clearly and at once why the situation of the metacentre must be higher in the sharp body than in the circular one. In the latter the breadth at the line of flotation is di, but in the former it is only ds; and as the extreme point of support in both bodies on one side is at d, while on the other side the support of the water extends to i, in the circular body, and only to s in the sharp one, it is very evident that the mean direction of the vertical effort of the water, which determines the situation of the metacentre, must be higher in the sharp than the full body, viz. at k in the sharp body, and at m in the full one.

b

It can also be easily shewn, that the more the vessels heel, the greater will be the proportional increase of sta'bility in the sharp one; for let emg represent the forces acting upon a circular bottomed vessel, m the centre of the immersed bottom, and consequently the metacentre, e the point at which the wind acts, g the centre of gravity of the vessel, then let the wind acting in the direction fb, incline the vessel to the angle bme, then the resistance will be according to the proportion of the two sines fb, ah. Now, suppose the vessel to be still farther inclined, as the point m remains stationary, the only increase of power, to resist the increased action of the wind is in the sine ah. But in the sharp body, supposing it to be still farther heeled, the position of the metacentre would be raised to n, the sine of the angle, at the extremity of which the gravity is supposed to act, would be lengthened, and the sine of the angle, at the extremity of which the wind is supposed to act, would be shortened, as shewn by

dg and ec; or, in other words, the resisting power would be greatly increased, and the motion considerably diminished.

With regard to a semicylindrical vessel, the objections to it are, 1st, That having parallel sides, she would not steer well. 2ndly, The metacentre being fixed, she would in her action resemble a pendulum, and consequently roll as much in a sea as to be almost unmanageable. 3rdly, She would be a very leewardly vessel, and not lay well on a wind. 4thly, The form of her after part would so retard her velocity, that, in my humble opinion, I cannot think that it would be overcome by increasing the sails to the very greatest extent the vessel would admit of; and with all due deference to Mr. Bland, I think it could never be practically adopted.

I remain, your obedient humble servant,

Cheltenham, Nov. 8, 1835.

H. W. ALLARDYCE, Bombay Engineers.

ORDERS OF GENERAL MONCKTON.

THE following extracts from an orderly book of the Hon. Lieut. Gen. Monckton, deceased, when an ensign in the 3rd regiment of Foot Guards commanded by Gen. Howard, then stationed at Ghent, show the strict injunctions laid by the commanding officers on the soldiers as to their behaviour towards the inhabitants of the country in which the army was quartered, as well as the attention paid to the clothing and accoutrements both of officers and men; and by comparing the dress and appointments of the present day with those of 1742, will exhibit the great improvement which time and experience have made.

7th June, 1742.

The clothing to be delivered to the battalion to-morrow at seven o'clock; an officer of each company to see the men well fitted with coats, particular care to be took in fitting them with shoes and hats. The waistcoats of the serjeants, corporals, drummers and sentinels to be made after the same manner as last year, and all to be made of the last year's coats; caps to be made also conformable to the orders of last year.

Every man in the battalion is to wear his ammunition shoes when on duty, and all under arms.

No man on any pretence to dispose of any of his new mounting, nor split or cut his rolls, but wear them as received.

No man to cut or alter the brims of his hat.

When the men are fitted with coats they are to have waistcoats on.

If any soldiers be found to disobey any of these orders, they will be severely punished by sentence of Court Martial.

None of the new mounting to be worn till Friday, the 11th of June, being his Majesty's accession.

June 8th.-If any officers or soldiers shall at any time meet the host carrying along the streets by the clergy of the town, they are to avoid it if they possibly can, by turning into another street; but if that cannot be done, they are to pull off their hats before they come near it, and stand still till it is past: no soldier is to laugh or show the least indecency on the occasion. The orders already given for the men to behave themselves decently in the churches to be duly observed, and no soldier on his peril to go into any of the churches before he pulls his hat off.

If the host at any time pass by any of the guards we mount, the men are to turn into their guard-rooms till it is gone, and if the host at any time passes by any of our sentries, they are not to keep walking, but stand still on their posts till it is gone by.

September 4th.-The Brigadier orders that on muster day all the men of the brigade do appear clean shaved and powdered, with gaiters, under arms.