S AW 



548 



SAW 



Sawing 

 Machinery. 



Common saw- 

 mill. 



PLATE 

 CCCCLXXXII. 

 Fig. 1. 



the atmosphere, and an ELECTROMETER* for measuring 

 small degrees of electricity. An account of his expe- 

 riment on the electricity produced by evaporation,t on 

 the electricity of the human body, and on the electri- 

 city of the atmosphere, have been detailed at great 

 length in our article ELECTRICITY, Vol. VIII. p. 427, 

 163, 479, and 481. 



Although the principal part of Saussure's life was 

 devoted to the examination of the Alps, yet he found 

 leisure to pay two visits to France, one for the pur- 

 pose of studying the extinct volcanoes of Auvergne, 

 and the other to make himself acquainted with the 

 practice of aerostation. He likewise paid a visit to 

 England, where he became acquainted with Dr. Fra- 

 neker. During a journey to Italy he visited the iron 

 mines of Elba; he measured the height of mount Et- 

 na, and he ascended Vesuvius in company with our 

 countryman Sir William Hamilton. Saussure was also 

 fond of botanical pursuits. He discovered several new 

 species of lichens, and two kinds of tremella having an 

 oscillatory motion ; and yet no genus has been dedi- 

 cated to his name. In our articles ALPS, Vol. I. and 

 CHAMOUNI, Vol. VI. p. 732, our readers will find 

 many of Saussure's opinions and descriptions of scenery. 



SAWING MACHINERY, or SAW-MILLS, is the 

 name given to all kinds of machines used for cutting 

 into pieces solid bodies, such as wood, stone, &c. 



Saw-mills seem to have been erected so early as 

 1420 in the island of Madeira. At Breslau, a saw-mill 

 was erected in 1427; and they were afterwards ra- 

 pidly introduced into different parts of Europe. 



A saw-mill, driven by wind, was erected at Leith 

 about the middle of last century ; and in 1767 or 1768, 

 when a saw-mill was erected at Limehouse, it was 

 demolished by the mob. 



In giving an account of sawing machinery, we shall 

 first describe the common saw-mill, which has been 

 long in use. This machine is represented in Fig. 1. 

 Plate CCCCLXXXII. No. 11. where BB is a bucket 

 wheel about 18 feet in diameter, and having about 40 

 buckets. This wheel is fixed on the axle A A, in 

 which there is also placed a wheel CC, having 96 teeth. 

 This wheel drives a pinion, marked 2, with 22 teeth, 

 which pinion is fixed on an iron axle, having a coup- 

 ling box at each end, that turns round the cranks D, D. 

 The vertical pole E has its lower end put on the crank, 

 while its upper end moves on an iron bolt at F, the 

 lower end of the frame G G. These frames, which 

 contain the saws, are thus made to move up and down 

 by the motion of the crank. The pinion, marked 2, 

 may give motion to two, three, or more cranks, and 

 may thus drive as many saws with their frames. A 

 ratchet wheel, No. 3. is fixed, as shown in the figure. 

 Its angular teeth are laid hold of by the end K of the 

 iron hook HK, the other end of which moves on a bolt 

 in the lever HH. The end of this lever moves on a 

 bolt at I, and the other rests on a notch in the frame 

 GG, so that it rises and falls with the frame. When 

 HH is raised by the frame GG, the catch K pulls the 

 wheel round towards it, and the catch Z falls into the 

 teeth, so as to prevent the wheel from going back- 

 wards. Upon the axle of the wheel 3 is fixed a pinion 

 4, which works on the toothed rack of the frame TT, 

 which carries the wood to be sawed. As the ratchet 

 wheel, No. 3. therefore, turns round, it carries the frame 

 T,T,which carrying the wood advanceson its rollers &,, 

 along the fixed frame UU, so as to come up against the 

 saws as they are moved up and down by the crank 



DD. The ordinary apparatus for raising the sluice Sawing 



and letting on the water, is shown at VV; but a self- Machinery. 



regulating one, such as that described in our article 'v^P^y-**^ 



HYDRODYNAMICS, Vol. XL p. 561, is used in all great 



establishments. By pulling the rope at the longer end 



of the lever M, the pinion 2 is connected with the 



wheel CC, which drives it, and, by pulling the rope K, 



they are separated from one another. In order to roll the 



frame TT backwards when it is empty, the pinion 5, 



with 24 teeth, and driven by the wheel CC, has upon 



its axle a sheave, over which is put the rope PP, which 



goes over the sheave O, and turns it round. Upon the 



axle of the sheave 6, is fixed the pinion 7, which acts 



on an iron rack upon the frame TT, and drives it 



backward. The pinion 5 is connected with the wheel 



CC, by pulling the rope at the lower end of the lever 



N ; and they are separated from each other by pulling 



the rope O. In order to drag the logs of wood in at 



the door Y, there is fixed upon the axle 9 a wheel 8, 



having ratchet teeth on its rim, into which the catch 



10 enters; and as this catch is raised by the lever at 



the upper end of the frame GG, it pushes round the 



wheel 8, which is prevented from moving backwards 



by the catch No. 11. falling into its teeth. The rope 



9 Y is, therefore, coiled round the axis 9, and thus 



drags the logs in upon the frame TT. The catches 



10, 11 are thrown out of play when the logs are laid 



upon the frame. 



Very great improvements have been made on saw. Brunei's 

 ing machinery by that celebrated engineer, Mr. Bru- improve- 

 nel. In our article on BLOCK MACHINERY, Vol. III. ments n 

 p. 608, we have already given a description of se- saw - mills 

 veral of the sawing engines, which form part of the 

 machinery for manufacturing blocks, and we shall now 

 confine ourselves to an account of the mo=t important 

 of his improvements. 



One of Mr. Brunei's saw-mills was constructed by 

 Mr. Maudslay, for the arsenal at Woolwich. It is 

 driven by a steam-engine; and the whole is considered 

 as a pattern of the best, as well as the most elegant 

 workmanship. 



in this machine leather belts are substituted most 

 properly in place of cog-wheels ; and in order to 

 equalize the motion of the cranks in the most perfect 

 manner, each crank has a fly-wheel attached to it, in- 

 dependent of the great fly-wheel of the steam-engine. 



In the construction of the saw-frames Mr. Brunei 

 has shown much ingenuity. They are all made of iron, 

 but the sides are left hollow, and are filled up with- 

 wood, in order to diminish the weight. 



As it is of essential importance that the saws be- 

 placed parallel to each other, and stretched with the 

 very same degree of tension, Mr. Brunei has effected 

 this in the following ingenious manner. The saws 

 are fitted into the frame, so that they can be quickly 

 removed and replaced by sharp ones. Each saw lias 

 a piece of metal rivetted to each end of it, and formed- 

 like hooks. The hook in the lower end is hooked into 

 a suitable recess in the lower cross bar of the saw- 

 frame, and the hook at the upper end seizes the hook 

 of a shackle or link which hangs upon the upper cross 

 bar, and has wedges through it, by which it can be 

 drawn tight to strain the saw. As there is nothing to^ 

 determine the parts of the cross- bars, where the hook* 

 of'the saws may hang, the saws can be set at any re- 

 quired distance from each other ; but in order to re- 

 tain them, pieces of hard wood are put in between the 

 blades of the saws at the upper and lower ends ; and 



# See ELECTRICITY, Vol. VIII. p. 522. 



f This subject has been recently pursued by M. Becquerel. See Dr. Brewster's Journal of Science, Vol. III. p. 370. 



