44 Aids to Microscopic Inquiry. 



instance, concentric crystalline layers ; but the concentric 

 lines, marking a succession of deposits, soon disappeared, and 

 left crystalline transparent masses whose cleavage was not 

 affected by the concentric layers : or rhombohedral figures 

 seemed to spring from the surface. 



If the solid molecules are not maintained in a condition of 

 moisture, the crystallogenic force is counteracted, and bodies 

 of little cohesion and no characteristic form is the result. 



In calcareous or silicious pastes, moistened with water, 

 diversely coloured by metallic oxydes or bituminous matters, 

 certain separations may occur, and the mass may be traversed 

 by crystalline veins of uncoloured calc or silicious spar ; hence 

 arise agates, jaspers, etc. In general the veinage of stones 

 may be considered as likely to have resulted from internal 

 movements, and not necessarily to have been occasioned by 

 accidental ruptures and subsequent infiltrations. 



After referring to other cases of an analogous nature to 

 those just mentioned, M. Kuhlmann inquires whether the ten- 

 dency of microscopic crystals in a sufficiently moist state to 

 solder themselves together in larger crystals, may not throw a 

 light on the formation of glaciers. The great masses of ice 

 have, for their point of departure* from the uncrystalline state, 

 microscopic crystals, which a certain degree of moisture permits 

 to unite when they descend from the regions of perpetual frost. 



AIDS TO MIOEOSCOPIC INQUIRY. 



Considerations prom Physics. 



Notwithstanding the many excellent works on the microscope 

 and its management, and on the various branches of natural 

 history which that instrument is specially calculated to eluci- 

 date, we find that young students and families still require fur- 

 ther aid, and we therefore propose to publish a series of articles, 

 written for the express purpose of removing difficulties which 

 numerous communications from all parts of the country prove 

 to exist, and in many cases to oppose a very serious obstacle 

 to a delightful and instructive pursuit. In following out this 

 plan, we must of necessity deal with the elements of many 

 sciences with which a great body of our readers will be fami- 

 liar; but while we thus address a portion of our pages to 

 beginners, we shall not fail to provide our more erudite sub- 

 scribers — as we have hitherto done — with a succession of 

 papers embodying the most recent discoveries, and presenting 

 science in its highest forms. 



