I. GEOLOGY. So 1 



preparation of thin sections of rock or other hard material for 

 microscopical examination. Designed by the exhibitor, and manu- 

 factured by Messrs. Cotton & Johnson, Soho. James B. Jordan. 



The machine c.onsists of a mahogany, oak, or beech framework (a a), 

 similar to that of an ordinary turning lathe, and is supplied with crank, fly- 

 wheel, and treadle, occupying a floor space of 2 ft. 2 in. hy 20 in. To the 

 bed of this frame is fitted an iron casting (B), bored to receive two spindles, 

 viz. : a vertical spindle (D), which carries the slitting disc, grinding laps, &c., 

 and another spindle (E), to which is fixed a horizontal plate (F), carrying 

 on its surface a cup containing cement, in which the material to be cut is 

 imbedded, and which is retained and uniformly pressed against the slitting 

 disc by means of a cord attached to the plate, which, passing over a pulley 

 having a suspended weight (G), gives a constant and regular pressure to the 

 plate containing the specimen. There is also a convenient screw arrangement 

 (K) by which this plate can be accurately adjusted for the purpose of regu- 

 lating the thickness of the slice. The slitting disc and laps are made to 

 revolve, at the rate of about 500 revolutions per minute, by means of a 

 treadle used in the ordinary way. 



3329. Apparatus for the preparation of rock sections, and 

 plates of crystals for examination in polarised light. 



R. fuess, Berlin. 



3330. Apparatus for the preparation of Thin Microscopic 



Sections of rocks and minerals : 



1. Cutting apparatus. 



2. Grinding and polishing apparatus. 



Christ. Weber, Eisenach. 



3353a. Ceteosaurus Oxoniensis. 



Left femur. 



Dorsal vertebra, 2 views. 

 Left huuierus. 

 Ilium, 2 views. 

 Dr. Acland, F.R.S., on behalf of the Radcliffe Trustees. 



3353b. Megalosaurus Bucklandi. 



Upper jaw. 

 Lower jaw. 

 Scapula. 

 Pubis. 

 Right tibia. 

 Ilium. 

 Caracoid. 

 Rib. 



Tschium, 2 views. 

 Sacrum. 

 Dr. Acland, F.R.S., on behalf of the Radcliffe Trustees. 



3H 2 



