If the timber is to be cut into planks, a number of circular saws are placed together on the axes of cc, with flanges between them of the thickness of the required planks, and then bolted together ; by these means the whole log is at one operation formed into boards; and if it be required to cut the logs into scantlings or laths, a series of horizontal saws I, placed in like manner upon a vertical axis In, and driven by a pulley n, cuts the whole at once into those small divisions. This mode of applying the saws to work in a horizontal plane so as to operate simultaneously with those acting in a vertical direction, forms the second impovement claimed under the ptent rit.
A third improvement claimed, is for uniting the plates of a series of circular saws closely together, so as to make one compact body of saws, without any interstices between them, for the purpose of reducing dye-woods entirely to saw-dust or powder, instead of the usual method of chipping or rasping them for dyeing or other purposes.
. • , • A few years ago (about a. s. 1820 Mr. Robert Eastman, of Brunswick Maine, U. S., invented some improvements in the construction of circular saws, and in the mode of sawing " lumber" (timber), which obtained extensive adop tion in America ; and as they appear to us extremely interesting, and that their adoption in this country would tend to beneficial results, we shall here annex the description, and the intelligent inventor's remarks upon the subject. Instead of a continued genes of teeth all round the periphery of the plate like othercircular saws,Mr.an's has only eight, or rather it may be said to have only four cutting instruments, each containing two teeth, which are placed at equal distances on the circumference, and projecting from it; these instruments are called "section teeth." The saving of labour in consequence of this form of saw, is calculated at full three-fourths; and the surface of the timber is much smoother than when cut by the full-teethed saw. On the saw-plate are also fixed instru ments called " sappers," which, being placed nearer to the centre, do not enter the wood so deeply as the saw, and are adjusted so as merely to cut off the extra neous sap part, rendering the edges of the planks uniformly straight, and all the cuts of equal dimensions. To understand which, it is, perhaps, necessary here to explain to the reader that the logs are, by this machinery, cut up lengthwise, owl through the log, but from the circumference, or exterior, to the centre, as the radii of a circle, it having been ascertained that planks, staves of casks, Ibc., cut out in this man
lier, possess much more dura bility strength, and elasticity, than by the common method. Fig. 1 represents a side view of the machine, with a log in it ready for working. ,Fig. 2 is an end view of the same, exhibiting the log partly cut into sections. Fig. 3 is the saw, with its section teeth L L L L, and its sappers M M. .Fig. 4 shows the shape of the sapper, with a groove, or slit, to adroit of its being set according to the intended width of the plank.
A, Fig. 1, is a strong frame of tins' her, about twenty-four feet long, by five broad, the ends of which are seen at A A, Fig. 2. B, Fip 1, is the carriag about twelve feet long, and four broad, the ends of which are seen at B B, Pig. 2 ; it travels upon iron truck wheels, grooved on their circumferences, and run upon iron slides, as shown at K K, Pay. 2. C. Digs. 1 and 2, gives two views of the log under operation.
The log is fixed into the carriage, by means of inn centres, upon which it also revolves, after each succeeding cut. At D D, .1Figs.1 & 2, is seen part of the saw. At E E, Figs. 1 & 2, are situated the feed pulley, *ad shifting gear. F, regulating pulleys. Ci is an index for regulating the dimensions of the cub. H, revolving levers and pins. I, the pin and fulcrum of the leven. J Jr, the stirrup screws and pins.
Nearly in the middle of the frame, is fixed the main shaft, of cast iron, which runs upon friction rollers, supported by stands on the floor. On this shaft is the saw, with its sappers and section-teeth. The motion is given by a band passing round the main pulley, and round a drum that runs under it ; which may be driven by horse, steam, or water power. The method by which the saw is fed with the wood to be cut, and the return of the carriage for the suc ceeding cut, is too similar to our own to need a particular description. Its various arrangements are ingeniously contrived, and it may be justly termed a self-acting machine, for when once set in motion, no other aid than the power which drives it, is requisite to its cutting a whole Bevies of boards, of uniform dimensions, all round the log, having their thin-edged sides attached to the centre-piece. These boards being removed, a second. series of boards may be cut in like manner to the former, provided the log is big enough.