416 



Monday, 21th March 1843. 

 Dr ABERCROMBIE, Vice-President, in the Chair. 

 The following communications were read : — 



1. Observations on the Temperature and Hygrometric state 



of the Island of Barbadoes. By R. Lawson, Esq., As- 

 sistant-Surgeon of H. M. 47th Regiment. Communicated 

 by Henry Marshall, Esq. 



This paper contains an account of the Thermometric and Hygro- 

 metric observations made at the Barbadoes, from May 1841 to Jan- 

 uary 1842. The instruments were carefully verified and observed; 

 and, during three months, the temperature was ascertained for 18 

 hours out of the 24. The author thence deduces the form of the 

 daily curve of temperature for that period. 



2. On the Growth and Migration of the Sea- Trout (Salmo 



Trutta). By Mr John Shaw, Drumlanrig. Communi- 

 cated by James Wilson, Esq. 



The author has here pursued the same course of experimental 

 enquiry regarding the sea-trout, as that formerly followed in rela- 

 tion to the salmon. Having obtained impregnated ova, from a pair 

 of spawning fish, he conveyed these ova to his experimental ponds. 

 This was on 1st November 1839, and the young were excluded 

 from the egg in 75 days. They resembled salmon of the same 

 ao-e, but were somewhat smaller and paler. They took two years 

 to grow about seven inches, and the majority were then converted 

 into smolts. But about one-fourth did not assume the silvery lustre ; 

 and this pecuUarity, ^Ir Shaw thinks, distinguishes a hke proportion 

 even in the rivers. He then experimented on the smolts in the 

 natural streams, and found, that, after descending to the sea, they 

 returned as herlings (^Sahno albus of Dr Fleming) in July and 

 August, with an addition to their weight of seven or eight ounces. 

 These herlings spawn towards the end of the season of their first 

 ascent; and, after revisiting the sea, they ascend the rivers again in 

 the ensuing months of May and June, with an average weight of 

 2| lb. This increase takes place almost entu-ely in the sea. After 

 spawning for the second time, they descend for the third time to 



