372 Dr. Green's Rcplj/ to Mr. J. de C So\\exhy\Remarh, S)X. 



the trouble to turn to the passage in your July Number, p. 37, 

 he will see that I have jiiven this as the opinion ot other ex- 

 perimentalists, whose names and works are referred to at the 

 bottom of the page. A considerable part of Mr. S.'s short 

 communication is to show that water will not pass through a 

 coik in the same manner as mercury through a block of woo^/, — 

 an opinion which I never maintained. 1 can however inform 

 Mr. S., that mercury in the pneumatic experiment of the mer- 

 curial shower will penetrate cork much in the same way as 

 it does blocks of wood ; and though not by longitudinal tubes, 

 yet in a manner sufficiently analogous to justify the compari- 

 son made by the gentleman I have quoted. 



Mr. S. concludes " from recorded experiments, that well- 

 fitted glass-stoppers will exclude the water." Now, for the 

 same reason, I conclude that they will not : and as I have some 

 authority for the fact, besides my own experiment, — which, by 

 the way, Mr. S. will not place among the recorded, — he must 

 produce further evidence. 



For myself, I am by no means satisfied with Mr. S.'s ex- 

 planation of the phaenomenon alluded to. How that part of 

 the cork which is protected by the neck of the bottle from 

 the lateral pressure of the sea should be diminished in its bulk 

 or diameter by the perpendicular or superincumbent pressure, 

 so as to be separated from the glass all around, is what I can- 

 not understand. So far from getting the cork throuijh the 

 neck ot the bottle, by Mr. S.'s mode of explanation it seems 

 to me that we shall only wedge it in the tighter. 



There is one part of the explanation proposed by Mr. S., 

 which struck me as a new fact. It is as follows : " Even pitch 

 when cooled in the deep water would be very brittle, and crack 

 or separate from the bottle readily; and it would assume its 

 former ductility and appearance upon returning through the 

 warmer surface {'warmer medium?). Now before this, I sup- 

 posed that common pitch melted at about 150" Fahrenheit, 

 and that the temperature of the ocean at a considerable depth 

 was much colder than at the surface. Even at the equator the 

 surface of the water is generally 80° Fahr., and it diminishes 

 as the latitude increases. At a distance from land, where our 

 experiments must be made, it also diminishes as the depth 

 increases. In a recorded and authentic experiment, it was 

 found that when the surface of the water was 40°, at the depth 

 of fifty fathoms the thermometer stood at 25°*. 



I could 



* We are at :ill times happy to insert the replies of writers whose papers 

 may have been tlie subjects of animadversion in our pages; but we think 

 that some ])assai;cs of Dr. Green's Reply to Mr. Sovveri)y, as above, require 



a few 



