288 SCIENCE IN SHORT CHAPTERS. 



the action of the wind which sustains and augments 

 them. 



. Quite recently, Captain David Gray made some experi- 

 ments at the north bar of Peterhead, where a very heavy 

 surf breaks over in rough weather. On a rough day he 

 dropped a bottle full of oil into the sea. The oil floating 

 out off the bottle, c&nverted the choppy waves over a large 

 area " into an expanse of long undulating rollers, smooth 

 and glassy, and so robbed of all violence that a small open 

 boat could ride on them in safety." 



This result is quite in accordance with what we are told 

 respecting the ancient practice of the fishermen of Lisbon, 

 who were accustomed to empty a bottle of oil into the sea 

 when they found on their return to the river that there 

 was a dangerous surf on the bar, which might fill their 

 boats in crossing it. 



As regards Peterhead, it is proposed to lay perforated 

 pipes across the mouth of the harbor, and to erect tanks 

 from which these pipes may be supplied with oil, and thus 

 pour a continuous and widely distributed stream into the 

 sea in bad weather. The scheme was mooted some time 

 ago, but I ana not aware whether it has yet been carried 

 out. Its success or failure must mainly be determined by 

 the cost, and this will largely depend upon the kind of oil 

 that is used. A series of well-conducted experiments upon 

 the comparative ^ areas protected by different kinds of oil 

 would be very interesting -and practically useful, for, until 

 this has been ascertained, a proper selection cannot be 

 made. How long will it last? is another question. 



I have frequently seen such tracks as Franklin observed 

 out at sea, and have climbed to the masthead in order to 

 sight the ship that produced them, without seeing any. 

 Several of such smooth shining tracks have been observed 

 at the same time, but no ship visible, and this in places 

 where no sail has been seen for days before or after. The 

 poet's description of " the trackless ocean" is by no means 

 "founded on fact." 



The Plymouth Breakwater contains 3,369,261 tons of 

 stone, and cost the British Government a million and a half . 

 The interest on this at 4 per cent amounts to 60,OOOZ. per 



