for becoming likewise charged with steam, and ascending in their turns, And I do declare that my said method of producing a rotary motion doth consist in the construction, use, and application, of the apparatus as here described and combined, namely, of the usual steam boiler or boilers, and of the receptacle, with its charge of hot water or other dense fluid, and of the combination of buckets, by a revolving wheel or by an endless chain and buckets, or by any other of the wellknown ways of applying buckets (in cases where the direct weight, and not the buoyancy of a fluid, is used as the first mover); and that the motion so produced in the shafts or arbors of the wheels round which the said buckets, in all and every such case and cases, must pass or revolve, in consequence of their successive ascent in the said heated water, or dense fluid, is the rotary motion meant and intended to be produced by my said new method; and moreover, that I do apply the said motion or force to mills, and to other useful purposes, by the usual and various means of connecting first movers with the several kinds of work intended to be done all which are too generally known and understood to be repeated in my present specification. In witness, &c.

On

On the distinctive Difference of Messrs. CHAPMANS' and Mr. CURR'S Patents for Flat Ropes.

Communicated by Mr. W. CHAPMAN in a Letter to the Editors.

GENTLEMEN,

HAVING

AVING observed, since the specification of the patent granted to myself and Mr. Edward W. Chapman, for the formation of "flat bands or belts to be applied to the drawing of minerals from mines," has been pubFished in your Repertory, that this invention has been represented in another publication so nearly similar to that of Mr. Curr, of Sheffield, for flat ropes, as to possess no very distinctive difference; I therefore feel it incumbent on me to state the grounds on which the patent for flat belts was taken out; and to say, that as a possessor of other patent property, exclusive of more liberal motives, I should be one of the last to think of infringing on the rights of others.

Mr. Curr expressly states that his method of making flat ropes is to lay two or more small ropes side by side, and to secure them in that position by stitching or interlacing, or by any other method; therefore, it is clear that Mr. Curr confined his invention to what he designed it to be; viz. a more useful combination of small ropes for the end which he proposed, than the making of one great rope for the same purpose; but by no means to preclude the stitching or interlacing together of other substances than rope, because the art of stitching and interlacing of things together was not of itself new. The question therefore rests on the distinctive difference between a rope and any of its component parts, particularly the strand of a strand-laid rope, which (well knowing that a

strand

66

strand is a terin occasionally applied to a strand-laid rope itself, when three of these are made into a cable-laid rope, by being twisted round their common axes), Messrs. Chapman have, to prevent misconstruction, described as being composed of any given number of yarns twisted together round their common axes; and which cannot of itself be called a rope, although a component part of one. I conceive that no one sending an indefinite order for a rope, would consider his order complied with if the rope-maker was to send him a primary strand composed of rope-yarns twisted together, which, when stretched at length and left to itself, would immediately open out. It would avail little for the rope-maker to say, you have only to cut the strand into three parts, and twist them together the contrary way, and they will then become a rope." He might with nearly as much propriety have sent the rope-yarns, or even the hemp, for each of them would have been constituent parts, but not the thing wanted. From these premises it clearly follows, that Messrs. Chapman's flat-bands, or strand-belts, are not made of ropes; but of a distinctly different thing zwhich they have defined; and consequently they can have no exclusive claim to any other description of flat bands, even if they were composed of rope-yarns, which are the immediate constituent parts of a primary strand, the same as the latter is of one description of rope, every kind of which is fairly included in Mr. Curr's patent; because a rope of any description is for its purposes a complete manufacture. It is evidently not so with primary strands for the reason already given, that the twist would open out, and they would become a loose body of yarns; therefore any new process of combining such strands together, or any new form when combined, is certainly

patent

patentable, more particularly if useful to the public; consequently, if Messrs. Chapmans' invention also possess this qualification, it has, as to distinctive difference, all that can be wanted. It appears that a strand-laid rope' composed of three strands, is one sixth part shorter than the strands it is formed of, and only twice the strength of a single strand. It therefore follows that in point of strength, or in reduction of quantity to produce the same strength, the invention must be highly advantageous to the public; provided the duration of strand-belts be, in any instances where they are applicable, nearly equal to that of flat ropes; and there is nothing in theory against their being completely so.

Prior to the inventions of either Mr. Curr or Messrs. Chapmans, flat bands have been made various ways in the different forms of girth-web made from untarred rope-yarn or hempen-yarn; but this application of yarn, or the application of this species of belt to the drawing of coals from mines, to which purpose it is not inapplicable, operates against neither of the inventions in question, although they are all composed of the same primary manufacture, viz. of hempen yarn, which is as distinct from a primary strand as such a strand is from a rope. The distinction may be still continued, although the process shall have approached much nearer: viz. allthe yarns for a strand stretched at length and bound together, so as to form what sailors call a salvagee, and which Duhamel and others have supposed to be the strongest mode of combining the strength of yarns*, may

..be

* A salvagee is much stronger than a common primary strand (the only one known when Duhamel and other authors wrote, who are quoted in the Encyclopedie), but inferior to a strand made on the

be used in any manner. The salvagee differs from a primary strand only in not being twisted, which is much nearer to a primary strand, than that strand to a rope. Yet I do not conceive that Messrs. Chapman could have a just plea to prevent any person so inclined from stitching these salvagees together side by side, and applying them to the drawing of minerals. Neither can they or Mr. Curr have any just plea to prevent any one from stitching together, side by side, knittles*, sennet, or gaskets (all of which are composed of rope-yarns), and applying the flat band thus made of them to the drawing of minerals, to which they would be perfectly applica ble. Messrs. Chapman contemplated all these combinations, and saw the relative imperfections of each, as well as those of ropes themselves laid side by side; and

new principle, by which all the yarns bear alike, or nearly so, at the point of breaking. This circumstance arises from the inequality of rope yarns, which if simply stretched in one mass, no otherwise combined than by ligatures, would, on a general tension of the whole, each of them break in its weakest part; but when twisted into such a strand as described, they combine one with another, and each ~ yarn bears its average strength, which, as the weak parts are generally à small portion of the length of each yarn, is much further be-' yond the least strength of each yarn than what is lost by the angle: they form to their common axis when twisted into a strand. Thus a primary strand made on the best principle is the strongest application of rope-yarns: therefore, any more advantageous combination of strands than has been used before must be a beneficial invention.

* Knitties are flat lines composed of three rope-yarns platted together. Sennet consists of fivé, seven, nine, or any larger uneven number of yarns, combined together in a platted form by a process not necessary to take up the reader's time in describing, but which produces some resemblance of two cylindric bodies connected toge ther. When his manufacture is made with an eye at one end, and tapered at the other, it is called a gasket, and is used, when shipsails are furled, to wrap round them, and bind them to the yards.

VOL. XIII.-SECOND SERIES.

G

having