413 



that the bees only produced as much honey as would keep the young bees alive, and 

 therefore when he found the bees were not making honey he removed it. 



Dr. Home said he did not think it was so much owing to the browsing of the cattle 

 as to certainty of food at all seasons. The very same thing had been observed in New 

 Plymouth, when he first settled there. The bees had plenty of clover, and when they 

 found that they could get honey in the wintei as well as in the summer they did not lay 

 up any. 



(3.) " On the Latent Heat contained in the aqueous vapour in the Atmosphere," by 

 J. A. Wilson.* This paper had appeared in the form of letters in the "Daily Southern 

 Cross," of November 19, 1864, and of December 24, 1S64, under the heading, "Ptemarks 

 on Australian and New Zealand Climatology, relative to our droughts, rains, and hot 

 winds." In his introductory remarks, Mr. "Wilson said that his opinions on the 

 subject were almost identical with those laid down by Professor Tyndall, in his famous 

 lectures on heat. 



Dr. Purchas said he had observed one kind of rain upon the leaves of plants, in very 

 large drops overhanging the edges of the leaves, and he could not say what was the reason 

 of it. 



Mr. Stewart said there might be a difference in the leaves ; if there was any in the 

 rain it would show in analysis, and might depend on the atmospheric state at the time, 

 and it might have a different effect on different plants. Mr. Wilson's paper had been 

 most admirably got up, and would require much time for discussion. With reference to 

 steam, the latent heat depends on the pressure of the steam, and it was ascertained by the 

 greater quantity of water that would be required to reduce the steam to a working 

 temperature, say of 100 degrees, and this even though the pressure of steam may be 

 reduced by expansion. 



Dr. Purchas said that we must recollect that steam at high pressure was a different 

 thing from steam at low temperature. High-pressure steam dissolves silica in caustic 

 soda, but low-pressure steam will not. As for the rain on the leaves, kind has nothing 

 whatever to do with the leaf, it is a peculiar description of rain, almost always 

 accompanied by sickness. When it happened he always observed there was something 

 very peculiar about the condition of the atmosphere. 



Mr. Peacock said it was a very valuable paper that Mr. Wilson had just read, and 

 would require consideration for some time. In reference to Mr. Stewart's remarks upon 

 steam, he, Mr. Peacock, was of opinion that the latent heat was not solely due to the 

 pressure. 



Mr. Stewart said his remarks had reference to steam produced in a partial vacuum, 

 where it could not flash like gunpowder into vapour at once. Ice wotild not immediately 

 dissolve when dropped into boiling water — latent heat requires some time to be reduced. 

 It was latent not so much in a partial vacuum, and conversely much more in a high- 

 pressure boiler. 



Mr. Wilson said Professor Tyndall gives latent heat as equivalent to concealed heat, 

 and he speaks of potential heat, possible heat, possible energy, possible power, dynamical 

 energy, which is temperature, etc. In lifting a weight, for instance, a certain quantity of 

 heat was expended in the action of drawing the arm up. We might speak of the 

 difference between two substances, and the atoms in that substance. Weight has a power 

 — a possible power. And if we take water, heat is a potent power in that substance, 

 keeping apart the molecules, and expanding it. When the potential energy passes off, 

 the actual energy takes place. Steam, for instance, can be evaporated at 32°, as well as 

 at any higher temperature. 



Captain Hutton said the paper was a most valuable one, and it was certainly a 

 curious question how the rain drops were so large when they fell, and how they came to 

 grow so rapidly in falling. 



After some further remarks the meeting adjourned. 



Fourth Meeting. August 16, 1869. 



T. B. Gillies, President, in the chair. 



The names of the following new members were announced : — Dr. W. W. Watling, 

 Dr. B. C. Beale, Dr. S. H. Ford, Mr. F. H. Meinertzhagen. 



A list of donations to the Museum was read by the Secretary. 



Papers read : — 



(1.) "On the Geology of the North Head of Manukau Harbour," by Captain 

 Hutton, F.G.S. (See ante, p. 161.) The paper described the formation of the locality 

 treated upon, which is composed chiefly of volcanic rocks. It contained an interesting 



* Sent to author for revision, 26th January, 1809 ; not yet returned, March 25.— Ed. 



