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MEMORANDA. 



Through the kindness of Mr. Jabez Hogg the editors are 

 enabled to present a drawing of this machine. 



Fig. 1. 

 The Cutting Machine. 



A A, consists of a stout brass frame, having an opening in the top plate. 



B. Orifice of a tube half an inch diameter and one and a half long. 



C. Loose piston working freely iu the tube, and steadied by the slot in the 



side. 



D. is a female screw, to which motion is given by the toothed wheel. 



E. The teeth, which answer the triple purpose of thumb-milling, ratchet- 



stop, and graduation. 



F. Block of wood, with rabbet to hold on the edge of a table. This machine 



is self-regulating, and may be worked as rapidly as the skill of the 

 operator will allow. It admits also of very fine graduation. 



Ne^v method of disintegrating ITIasses of Fossil Diatomacese. — 



Many masses of fossil Diatomaceae are so strongly coherent, 

 that they cannot be diffused in water, (for the purpose of 

 mounting in balsam,) without a degree of mechanical violence 

 which reduces to fragments many of the most beautiful and 

 interesting forms. This is particulax'ly the case with some 

 specimens from the " infusorial deposits " of California. Some 

 of these I endeavoured to break up, by boiling in water and 

 in acids, and also by repeated freezing and thawing when 

 moistened, but without good results in either case. At last it 

 occurred to me that the adherence might be due to a slight 

 portion of a siliceous cement which the cautious use of an 

 alkaline solution might remove without destroying any but 

 the most minute shells of the Diatoms. As the case appeared 

 a desperate one, a " heroic remedy " was applied, which was 

 to boil small lumps of the diatomaceous mass in a strong solu- 

 tion of caustic potassa or soda. This proved to be perfectly 

 efficacious, as the masses under this treatment rapidly split up 

 along the planes of lamination, and then crumbled to mud, 

 which being immediately poured into a large quantity of 

 water ceased to be acted upon by the alkali, and gave when 

 thoroughly washed, not only all the large shells of the Diatoms 



