272 GEORGE HOGGAN ON A 



move from the correct position, and the saw cnt which cuts off one 

 section forms the parallel plane for the next. 



Ijet us now take the case of bone sections. The same authors 

 advise us to take a bone and saw a bit off it in the ordinary way ; 

 this may average i of an inch thick. We are then to file it down 

 as thin as possible without breaking it (this will probably stiffen 

 our fingers) ; it is next to be rubbed down on an oilstone, and 

 should the pulp of our fingers give way under this operation we 

 must use two oilstones, between which the bone is placed, while the 

 two stones are rubbed against each other. (In the College de 

 France two pieces of pumice stone are used for the same purpose.) 

 You may thus, perhaps, succeed without any breakage in making a 

 section after two or three hours' labour, which is ready for mount- 

 ing, and it will look very well indeed, as far as the sharp definition 

 of light and shade is concerned, for every lacuna and Haversian 

 canal is filled up with the black dirt or debris of the oilstone, giving 

 a sharp enough outHne certainly, but not on that account a true 

 idea of the bone substance which you wish to examine. 



With my machine a piece of bone, say 1 inch square and of any 

 length, is placed on the table in the same way as in the case of the 

 tobth, and you may then proceed to make sections, which may each 

 occupy five minutes at most in cutting, and they are then ready for 

 mounting. The sections I now show you, about -J inch square 

 were made from the head of the Tibia, while a friend stood by 

 and noted with his watch the time taken to cut each, while I made 

 a dozen sections, and we found that each occupied from 2^ to 3 

 minutes, the dozen being completed within 40 minutes. The saw- 

 dust was then washed off, and they were mounted without further 

 preparation, and I leave you to institute a comparison between 

 these and the old processes. 



In sawing, however, I wish to draw your attention to a most 

 important point — namely, to have the teeth of the saw directed 

 towards yourself, and to saw when drawing back, not when pushing 

 forward. I cannot well conceive a more vicious and unmechanical 

 mode of using a saw than that generally practised by Europeans, 

 in having the saw-teeth directed from the workman and sawing as 

 it is pushed from him, working thus in the worst possible position 

 for the application of both power and precision. 



In my younger days I was sent to learn carpentry, and 1 still 

 remember, with a shudder, the aching arms, the deviating saw 



