Contents xxxix 



PAGE 



through it objects which would be clearly perceptible 

 under less powerful illumination. 



Sunset of 27 October, 1883, behind the Peak of 

 Teneriffe, distant 115 miles ..... 250 



Remarkable effect of reflection by waves. 



Sunsets less brilliant on land than at sea . . ..'51 



The sunrises presented no unusual feature. 



Variable visibility of the Peak of Teneriffe at a dis- 

 tance of seventy miles before and after sunrise. 



Analogous phenomenon well known to Pilots. 



Difficulty in accepting the usual explanation of these 

 remarkable sunsets . . . . . . .252 



No. 15. SIR LA DF.NSITE ET i AM AUXIN: DBS I.AUX DE 

 L'ATLANTIQUE ET DE LA MEDITERRANEE. [From 



CompUs Rendus, 1893, Vol. i-xvi. p. 1321] . 254 



This is an account of a series of simultaneous deter- 

 minations of the density and the alkalinity of samples 

 of sea-water taken on a voyage from Dartmouth to 

 Genoa, in the months of August and September, 1892, 

 in the steam-yacht " Princesse Alice," which had just 

 been built on the Thames for His Serene Highness 

 Prince Albert I of Monaco. 



The yacht was fitted with all the engines and 

 apparatus for exploring and investigating even the 

 deepest seas of the ocean. 



The Prince's long experience in this class of work, 

 carried on in the "Hirondelle," a schooner of only 200 

 tons, made him, without question, the highest authority 

 on the practical details of deep sea investigation. The 

 more primitive fittings of the "Hirondelle," on which 

 everything was done by hand, were replaced by steam 

 winches and wire lines and cables, and every novelty 

 .tnd invention \\hic h his experience suggested. 



His Highness .'.id me the great honour to invite me 



accompany him and to work with him on board 

 during the opening cruise to Genoa where I had the 

 privilege of assisting as a guest of His Highness at the 

 magnificent fetes given by that city in honour of the 

 four hundredth anniversary of the Discovery of America 

 by tin- most lam..! < hristopher Colombo*. 



\pparalus and of e\ pel imental 



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