The improvements to which the attention of our readers is invited in this article, and which are illustrated in the accompanying engravings, are, in our opinion, the most important recently made in methods for hanging mill saws. These improvements, however, not only include the hanging of the saw, but an inspection of the engravings will show an important change in the saw itself. The objects sought in these improvements are five ; namely, to do away entirely with punching or drilling saws at the mill ; to allow the strain to be placed at any desired part, and to be gradually changed as the saw wears away ; to enable the sawyer to adjust the “ rake” of the saw, or, as it is commonly styled, the “overhang,” in a very short time ; to permit the employment of thinner saws and thus reduce waste in the kerf; and, finally, to obviate the objections against the exclusive use of fine teeth, or of coarse teeth, on such saws, by a compromise between them ; the teeth at the upper part of the saw being coarse and gradually becoming finer toward the bottom. We shall treat the means by which these objects are attained in the order of their statement ; but we ought, perhaps, to state first that they are the result of long experience in the cutting of lumber, and that an intelligent analysis of first principles has been brought to the aid of experience in bringing them to their present state of perfection. The punching of the saw at the mill is avoided by placing over the end of the saw a piece of metal, the form of which is shown in Fig. 2, drilled and permanently riveted to the saw. Upon this piece of metal is slipped the hook shown in Fig. 3, the slot, A, of this hook being made to admit and fit closely the metallic piece shown iu Fig. 2, and a short portion of the saw blade below it. The bearing at the upper part of the slot, A, is curved, as shown at the dotted line, I, Fig. 5, to permit parallel strain in adjusting the overhang. Fig. 3, however, is the hook used at the bottom of the saw, while Fig. 4 represents the application of the same method to the upper end of the saw blade; the shank, B, of the stirrup passing through the upper girt ofthe saw gate, and being keyed up in the usual manner, as shown at C, Fig. 1. A metallic plate, D, bolted to the lower girt, Figs. 1 and 5, and grooved to fit the hook, as shown in section at Fig. 5, forms the means for making the attachment of the saw at the lower end. These attachments are shown at F and G, Fig. 1, parts being broken away for the purpose. This engraving gives a good representation of a gang of saws mounted in the manner described. It will now be seen that any desired rake, or overhang, may be given to the saw, and that the strain can be placed at any desired part by simply tapping loose the keys, C, and sliding the blade in the slots A of the hook, Fig. 3, or the stirrup, Fig. 4. These advantages lead naturally to the securing of the fourth object above enumerated; namely, the employment of thinner saws than could otherwise be used, as the strain may be adjusted in a line parallel and very near to the teeth. The distance between the saws is -regulated by the bars, H, having slots sawed on their inner edges to fit the thickness of the blades. The manner in which the fifth object sought is attained has already been stated in general terms ; but as this involves a new principle in the construction of mill saws some further explanation is needful. It is well known that hand rip saws are made with coarser teeth at the heel than at the point, or so that fine teeth commence and coarse teeth finish the cut. Fine teeth cut at the outset much more smoothly than coarse ones, but as soon as they become clogged with sawdust they lose their efficiency to a great degree. As this partial clogging becomes most troublesome at the latter end of the stroke, the arrangement adopted in these improvements brings the larger teeth into play just where they are needed, and obviates the rank tearing of coarse teeth at the commencement of the cut, and reduces the amount of splintering at the bottom of the kerf, Thus a much smoother action and better work are obtained. These improvements have secured the warmest approval from some of the most extensive lumber manufacturers in the United States. Among these we may mention Benjamin W. Thompson, superintendent of the celebrated Dodge Mills, Williamsport, Pa., and J. G. Marvin, foreman of the same, who state that they should be very unwilling to dispense with their use. Numerous other testimonials from prominent men in the lumber trade. have also been shown us, which leave no room for doubt as to the value of the improvements. It is almost unnecessary to mention that these improvements may be adapted to double hook gates as well as to single hooked ones, or that the attachment shown in Fig. 2, when clasped and riveted to the saw, must greatly strengthen the plate. They are also equally applicable to muley saws A patent for the improvements in saw hangings was obtained April 21, 1868, one on the improved construction of the mill saw, December 29, 1868, and on the strap or tab, June 1, 1869, by E. Andrews, of Williamsport, Pa'., who may be addressed for further information. S. H. K., of Ky., sends us a sample of eggs of the Hear Horse, and says, “ In your current volume, page 181, I notice a cut and concise history of the Rear Horse. They have been known to me by the name of 'Devil Horse.' I have always been afraid of them, not because they ever did me any harm, but because they looked as if they might if they had a chance, and I have always killed them. The mother of this bundle of eggs, I suppose I killed only a few days before I received your statement about them. It is a source of relief to me to know that they are harmless, as I frequently meet them. provements, however, not only include the hanging of the saw, but an inspection of the engravings will show an important change in the saw itself. Dynamite.—A correspondent writing from St. Louis, says, “Will you please, in your paper, inform venders of “Dynamite “ that a subscriber thinks if they would advertise with you, they would increase their sales ?'' © 1869 SCIENTIFIC AMERICAN, INC. October 16, 1869.] $mwm it MUNN&COMPANY, Editors and Proprietors. PUBLISHED WEEKLY AT NO. 37 PARK ROW (PARK BUILDING), NEW YORRi O. n. lIlTiNN. P. H. “WALES, A.E. BEACH. The American News Company,” Agents.121 Nassau. street.New York. The New YorkNews Company,” 8 Spruce street. Messrs. Sampson, Low, Son&Marston, Crown Building, 1S8 Fleet st.; Tubner&Co. , 60 Paternoster Row. and Gordon&Gotch, 121 Holborn Hill, .London, are the Agents to receive European subscriptions. Orders sent to them will be promptly attended to. them will be prouiptly attended to.__ VOL. XXI., No. 16 ... [New Series.] ... T'wenty-fourtUYear. NEW YORK, SATURDAY, OCTOBER 16, 1869. Contents: (Illustrated articles are marKed with an asterisk.) Address of the Hon. S. S. Fisher, U. s, Commissioner of Patents, before the American Institute.241 Roquefort Cheese_________...........242 Spontaneous Ignition in Woolen Mills..............................243 The Boiler Explosion at the Indiana State air...................2 43 The Manufacture of Steel..........243 Sii'mcns on Patents.................244 *Maclc's Improved Feed-Water Heater............................244 A New Alarm Bell for Locomotives...............................244 "Improved Cotton and Hay Press.245 Nervous Dyspepsia..................2 Impaired Taste......................24% The August Meteors................'245 The Manufacture of Sulphuric Acid..............................226' ei from Friction...................246 The Gerner Boiler..................246 ('tm. the Flow of Elastic Fluids......246 Business Correspondence____......247 n4 Determinationof the Amount of Expansion of Mineral Oils.....247 WhyCoffee is a Stimulant..........247 Advertising Made Easy.............247 *Denmth's Improvement in Glass The Drive Wheel. ......1 ::::::::::::248 *Aiidrew's Patent Saw Hanging:"! and Saws.........................248 The Hydrostatic Parti dox..........249 The Wandering of Phosphorus in The^hMtion of the: AnKrYcanln-stitnte ...........................249 Annual Report of the President of the Western Union Telegraph Company.........................251 Return ofC. F. Hall, the Arctic Explorer.........................251 The Natural Advantages of Tennessee for the Production of Iron...............................251 How to File and bet a Saw.........252 A Patents...........................252 The Torpedo Patent Case..........2352 Kecent American and Foreign Patents..............................252 t e 53 Inventions Patented in England by Americans....................2354