SOME IMPORTANT CONCLUSIONS. 261 



the warm temperature of the surface of the sea on the 

 Irish coast particularly adapts it for oyster-breeding ; and 

 the following conclusions are put forward in a paper by 

 Professor Hennessy : 



" 1. The temperature of the sea on the coast of Ireland 

 varies within narrower limits than on the coast of Great 

 Britain; or, in other words, it is more equable -through- 

 out the year, and also during the summer season, when, 

 oyster-breeding takes place. 



" 2. The temperature of the sea at noon on the Irish 

 coast, especially on the south and west coasts during the 

 months of June and July, is, upon the whole, higher than 

 on the coast of Great Britain, and less than on the west 

 coast of France. 



" 3. This temperature seems to be sufficient for the re- 

 quirements of oyster-breeding. 



" 4. The highest temperature of the seas surrounding 

 Ireland, and probably also of those surrounding Great 

 Britain, is during the month of August, and the least 

 during the month of February." 



The Commissioners also publish some conclusions arrived 

 at by Professor Sullivan in reference to the composition of 

 the soils of oyster-grounds : 



"1. That the influence of the soil upon the breeding 

 and growth of oysters is complicated by temperature, 

 especially during the spawning-season ; sudden alterna- 

 tions of heat and cold, due to currents ; alternations of 

 depth of water, especially as regards whether the maxi- 

 mum of sun heat and light concords with low water 

 during the spawning-season ; velocity of tide, angle of 

 inclination of shore, &c. 



" 2. That the soil of oyster-grounds may be made up 



