Were it necessary, it would be an easy matter for me to prove, by a hundred circumstances, that Mr. Smith was acquainted with all that was done by Mr. Don and myself in the manufacture of these shutters; but I shall content myself with stating one or two other incontrovertible facts, which alike prove that the invention, originated with myself, and that Mr. Smith knew of it.

In the month of December 1828, I superintended the fittingup of the shop of Mr. Westwood, in Princes Street, Haymarket, with my metallic shutters; but, owing to a trifling imperfection in the work, an unpleasant noise was made in drawing up the shutters about a week afterwards. At this time, Mr. Smith, who was previously acquainted with Mr. Westwood, called to look at the new shutters, when Mr. Westwood requested him to examine the movement, with the view of ascertaining the cause of the noise; he did so examine it, and the inconvenience was removed.

About this period Mr. Don experienced some severe misfortunes (owing to his confiding and generous disposition), which led to the public sale of his stock and manufacturing implements. At this sale Mr. Smith was present, and actually purchased several models, and the whole of the drawings, of the metallic shutters, for the sum of nine shillings!

Thus equipped with all the materials for a patent, Mr. Smith becomes a patentee, and repeats, in his specification, the solemn declaration that the invention was perfectly new, and was before practised in these kingdoms."

66

never

As the facts I have stated are incontrovertible (and such as any body may satisfy themselves of, by reference to the parties mentioned), I shall not adduce any others, but proceed to shew the identity between my invention and that which Mr. Smith has since patented, which I cannot do better than by copying your concise and clear explanation of the patent given in your last Number, inserting only a few letters of reference, which exhibits, in the clearest light, that there is no variation whatever in the arrangements.

The accompanying drawing (plate V.) represents an elevation of the front of Messrs. Hankey's Banking-House (correct to scale, as respects the shutters, and the windows to which they were applied). The window, as will be observed, is divided into two equal portions; that on the right-hand side of the leader is represented as being closed up by the metallic shutters, and that on the left is represented as having certain portions of the wooden casings broken away, to exhibit the movement, to explain which, I shall, as before said, use your words descriptive of Smith's patent.

"These improvements in shutters consist in alterations of the arrangements and operations of the apparatus connected with the patent metallic shutters described at length in the second volume of the new series of the REGISTER OF ARTS. Instead of the shutters being raised or lowered by cords or chains passing over pullies, as there described, the present patentees PROPOSE to employ screws extending from top to bot

in my

tom, on each side of the window," (as shewn at letters a a, drawing,) "a simultaneous motion is effected in the screws, by means of a bar extending across the bottom of the window," (see letters bb) "and connecting by bevil wheels," (see letter c,) "both screws with a winch handle, (d) by which they are turned. Upon the screws are fitted, nuts, (e) "to which are attached the shutters," (fff, which hook into each other,)" and, therefore, by the operation of turning the handle, the shutters are steadily and silently raised in front of the window, or lowered into their case."-Here ends the description as applicable to my improvements; but you further observe, in continuation, shat "the patentees mention some variations in the construction of this apparatus, such as endless chains passing over spiked wheels, instead of the screws for raising the shutters, or instead of the bars and wheels for transmitting the motion from one side of the window to the other." Now, in this last-mentioned plan, Mr. Smith is equally, or more, in fault than in the other for he knows well, that it was tried at Messrs. Hankey's, and failed; and in consequence of such failure, was taken down, and the screw machinery, introduced by me, substituted in its place.

;

The operation of the present apparatus having given unqualified approbation, Messrs. Hankey are now employing Mr. Thomas Thomas to fit up the remainder of the front of their premises in Fenchurch Street in a similar manner. The shutters for this purpose, are completed ready to put up, and may be seen in the manufactory of Mr. Thomas, (in Holland Street, Blackfriars,) to whom I have communicated fully my methods of constructing and manufacturing; and I have no hesitation in assuring the public, that there is at present no other person so competent, in every respect, to execute work of this kind.

Your obedient Servant,

JOHN MAC DOWALL.

Observations by the Editor.-We have made a call at Mr. Thomas's manufactory, and examined the metallic shutters constructed for Messrs. Hankey, in which we cannot discover the slightest difference from those which we saw described in Messrs. Kitchen and Smith's specification. The security afforded by this admirable invention is such, as to entitle it to adoption wherever property is liable to the depredations of the burglar. Its operation is steady and uniform; and from its great simplicity and strength, it is almost impossible to be put out of order. The shutters being attached to the vertical screws by large nuts, it is evidently impossible to force them up or down, with any power that could be applied by burglars; while, by the application of a little winch inside the premises the operation of raising or lowering the shutters may be easily performed by a child. The great durability of these shutters renders them much more economical than those of wood, notwithstanding the first cost of the latter is somewhat less.

EXPERIMENTS WITH STEAM-BOAT PADDLES.

BY THE EDITOR.

NOTWITHSTANDING the very numerous plans that have been proposed to improve the propelling apparatus for steam-boats, by substituting other machinery for the ordinary paddle-wheel, we do not hear of any of them being adopted. That a great loss of power is sustained, owing to the paddles entering and leaving the water at an unfavourable angle, when they are placed in the position of radii to the circle cannot be disputed, though its amount is variously estimated, and in reality they do very considerably under different circumstances; for, if the diameter of the wheel be very large, and the depth of immersion very little, the disadvantages mentioned are so trifling as to render the adoption of an apparatus that is more complex, less strong than the common wheel, by no means eligible.

With the view of ascertaining whether the common wheel could not be improved, without materially altering the simplicity of its structure, we instituted some experiments a few days ago, which, we are happy to say, were attended with results so satisfactory, that we propose to renew and extend them, with apparatus on a larger scale. That which was employed in the experiments we are now about to describe, consisted of a kind of double boat, formed out of two solid pieces of wood, each about 30 inches long; they were shaped at the head and stern like a common coal barge, and were secured together, by nailing across the ends, on their superfices, two slips of wood, which kept them about 8 inches apart; into the recess thus formed between these two representatives of boats, were placed successively the models of five differently formed wheels, (shewn at plate VI. by figures 9 to 13.) They were made of tinned iron plate, and all of the same dimensions, namely, 7 inches diameter, 3 inches wide, and the paddles 1 inch deep. A tube was formed through the centre, for a moveable axis, which was, therefore, made common to them all; the ends of the axis turning in plummer blocks fixed to the inner sides of each boat. The power was applied by means of two weights descending from two pullies fixed in a frame above, the lines of which were wound round the axis of the paddles on each side, to keep the apparatus equipoised; a strong thread was attached midway between the sterns of the two boats, and the other end was wound upon a little reel. The trial was made upon a large basin of still water, on a calm day.

The wheel, No. 9, in which the paddles are bent into right angles, and the sides inclosed being put on the axis, the weights wound up, and every thing carefully arranged to prevent, if possible, the error of a second of time, notice was given to let go; the weights, then descending, propelled the machine by the revolution of the wheel, which drew out 28 feet of thread in 37 se