PEIZE QUESTIONS OF SCIENTIFIC SOCIETIES. 447 



the canals, or water-courses, showing their lengtlis, their transverse 

 section, and the obstructions whicli may influence the discharge of 

 the waters. To these particuhirs there should be added a historical 

 notice of the various projects for the improvement of draining ; such 

 notice to indicate the results of such projects in the cases in which 

 they have been carried into execution. Finally, there should be 

 a description of the means of defence against the exterior waters 

 and the results obtained from the means employed. 



2. Question 106. This society, judging that the examination of the 

 temperature of the water of the high seas taken at considerable 

 depths may be of muph importance in conducing to a knowledge of 

 the physical state of our globe, and knowing that on board of many 

 vessels, under favorable circumstances, this temperature can be ascer- 

 tained, solicits careful research upon this point; such research, with 

 proper apparatus and appliances, to be made in latitudes and longi- 

 tudes in which it has hitherto not been undertaken; and this society 

 further solicits succinct and formal yet fully detailed reports of such 

 researches. 



3. Question 111. It is undeniable that the crystalline form is one 

 of the essential properties of matter, but in the present state of our 

 knowledge we possess only an imperfect idea of the relation which 

 truly exists between the crystalline form of a body and its chemical 

 composition. 



Crystallographic examination, properly so-called, has hitherto been 

 for the most part limited to objects presented to us by nature in the 

 form of minerals, while we have only a superficial acquaintance with 

 what we may know about crystals artificially obtained from chemical 

 compositions or simple bodies. 



The rjesults obtained from the crystallographic examination of min- 

 erals cannot develop generally admissible natural laws, because we 

 are very imperfectly acquainted with the conditions under which 

 they are formed and the medium from which they are produced. 



As in the artificial formation of crystals we are in every respect 

 better able to 'ascertain the conditions and the medium, it is pro- 

 posed that — 



"A crystallographic and rigorously conducted examination be made 

 of such inorganic substances as assume the crystalline form suffi- 

 ciently to allow of cleavage; 



"An inquiry be made into the circumstances under which the 

 crystalline form of the selected substances has been modified; and 

 this not only as to the secondary, but also as to the primary or type 

 form." 



"A critical review be made of the crystallographic description of 

 different authors of inorganic substances, with respect to both the 

 primary and the secondary forms." 



"That the progress be stated which has been made towards obtain- 

 ing a knowledge of the connexion between the crystalline form of a 

 substance and its chemical couiposition. What obstacle exists to 

 our obtaining this knowledge by the way of experiment?" 



