Why not in all these branches of trade describe every thing measauring 1/16th of an inch, as No. 10; those of 5/16ths inch, as No. 30? and then in sets of objects required to be nearly alike, the succeeding numbers could be 31. 32. 33.34.35. 36. etc.; or if fewer and wider variations were wanted, the series might be 32. 34. 36. 38. 40.; or else 35. 40. 45. 50. 55. Every trade could select any portion of the series it might require, both as regards general magnitude, and the greater or less intervals between the sizes, and with the power of adding to, or subtracting from, the scale first selected, as circumstances might suggest.
But there should be one common understanding that the commercial numbers or sizes, when different from the measures of the foot-rule, should be always understood to be hundredths of the inch, (in some rare instances thousandths,) as then from the unity of system no confusion or difficulty could possibly arise.
It may be true that some of the proposals having reference to the weights of materials in the superficial foot, the correspondences with foreign measures, and some of the projects principally intended for the purposes of science, may not be required in every-day practice: but still much remains in the system, that in the opinion of the author, would admit of very easy introduction, and most general and satisfactory employment
In respect to the practical application of the method of decimal divisions, as regards mechanical construction, the author can speak most satisfactorily from some years' experience in his own manufactory, as he has found it to be most readily followed by his workpeople, and also that it has avoided frequent and vexatious misunderstandings, to which, before its adoption, he was frequently subjected, from the want of a more minute and specific system of measure, than is afforded by the common foot-rule and wire gages.
Therefore, from conviction of the usefulness and practicability of the decimal system of measures for small quantities, he would moat strongly urge its general, or indeed universal, adoption, as above proposed: the more especially as it is a change that would be attended with very little temporary inconvenience or expense, circumstances which greatly retard all attempts at generalisation.
Mr. Bodmer's Patent mode of constructing the inner and outer tires of locomotive wheels, and other annular objects, might possibly serve for making in one piece the riband saws spoken of at page 751, and also the crown saws represented and described fig. 797, pages 802 - 3.
In making the tires of locomotive wheels, the first course is to prepare a mass of wrought iron of the appropriate weight and with a central hole; this rude annular piece of iron, when raised to the welding heat, is inserted between a pair of rollers that overhang the bearings in which they work. The one roller is placed within and the other without the piece of iron, which, however irregular, is soon thereby reduced to an equal section throughout when the rollers are set in motion; and a third roller, placed in the path of the nascent hoop or tire, gives it a form almost as truly circular as if it had been turned in a lathe. The three rollers ensure circularity in the tire upon the same principle that is employed in the three bending rollers, see fig. 232, page 399, Vol I
Note BO, page 803. - To follow the third paragraph. (Mr. Harvey's Patent Curvilinear Saws.)
Mr. Harvey took out a patent in June 1845, for an adaptation of the cylindrical or crown saws, described in pages 800 to 803, by which they may be applied to works of indefinite length. The hoop constituting the saw, is attached to a disk mounted on an axis, but the disk only extends over 3/5 of the circumference, leaving 2/5 exposed for the passage of the wood; And the saw instead of receiving continuous circular motion, as before, is now reciprocated by a crank through a few degrees only of the circle, so that the wood sawn off may proceed through the aperture between the saw and the disk; which aperture somewhat resembles the space between the spokes of a wheel having three arms and a very thin flat rim.
The square log fig. 1025 is mounted on centers, upon a drag or slide, fitted with rack, pinion, ratchet and detent as usual for feeding the cut, so that the log is presented with its four angles successively; and the oxtreme edges having been first sawn off with an ordinary circular saw, also attached to the machine, the four annular sections a a a a, are first removed from the four angles, then four larger b b b b, with a saw of greater diameter, and afterwards four others c c c c, the nucleus e, is then sawn in two, and the several pieces when recombined produce the mast of the section fig. 1026, which is said by the Patentee to be much stronger than any mast or spar consisting of a single piece of timber.
The inventor also proposes to apply the saws to short works such as chair backs and brushes, but which may be apparently better produced in the old drum saw, which acts more rapidly from receiving continuous motion - he also proposes to cut pieces of double curvature or of the ogee form, by the employment both of the inner and outer surfaces of the cylindrical saws according to circumstances. See Mechanics' Mag. 1846, Vol. 44, p. 18.
The reader is referred to Note BN, which suggests a new mode of constructing cylindrical or crown saws.
Note BP, page 827, to follow the paragraph ending "fast by each foot."
To this paragraph it should have been added, that in cutting the ends of the files, which parts must necessarily be laid at the time upon the anvil, the opposite end of the blank is supported upon a wooden prop of the same height as the anvil, and the straps are placed in the middle of the length of the file.