SEA-FISHERIES LABORATORY. 99 



Man. This is now accounted for by the following explana- 

 tion. Daring transit some of the bottles were broken, 

 but in order that the post cards should not be wasted, 

 other whole bottles were obtained, the card and the same 

 sand put in, then the whole sealed up, over-looking the 

 fact that all bottles may not be of the same weight, each 

 requiring careful ballasting, consequently when these 

 bottles were thrown overboard the majority of them 

 sank. 



The result of this experiment of Mr. Ascroft's showed 

 that weighted bottles tended to go south, thus differing 

 from the light ones, which largely went to the north. In 

 order to throw further light on this apparent southerly 

 drift of weighted bottles, it was decided to give the 

 weighted bottles a further trial, and in addition, by set- 

 ting them free on the spawning grounds when the steamer 

 was trawling for spawning fish, perhaps gain some definite 

 information regarding the direction of the drift of the 

 surface waters in which the embryos and larval fish 

 usually are. 



Accordingly we had a number of ordinary post cards 

 having the same notice previously used, printed on the 

 back, and we purchased a supply of bottles, known as ''cocoa 

 wine bottles," of about one pint capacity. These bottles 

 were placed one by one floating in a bucket of sea-water 

 of 1*0026 specific gravity, and then carefully ballasted with 

 dry sand, so that when the rolled up and numbered post 

 card was placed inside, the cork inserted, and the whole 

 sealed up with paraffin wax, only about an inch of the 

 neck of the bottle was above the surface of the water. 

 They were then sent on board the fisheries steamer in 

 batches, each batch being accompanied by forms having 

 the numbers of the bottles, and spaces for the insertion of 

 the position of the steamer when the bottle was set free, 



