no On Similarities in the 



collection was then sent by Mr Murray, with the result that 

 Professor Hartley detected chlorophyll in it also. The diatoms 

 so abundant in the surface waters of Antarctic regions give 

 the water and the ice exactly the colour which is to be found 

 in the coast waters of windward shores. It would be a matter 

 of great interest to determine, by careful observations and 

 investigation, if the green colour of these coast waters is directly 

 or indirectly due to the presence of chlorophyll. 



A most remarkable confirmation of the view that the cold 

 water on the windward shores is due to a submarine source 

 has been quite recently supplied by the observations of 

 Captain Hoffmann of the German man-of-war "Mowe, 1 ' on 

 a voyage from Zanzibar to Aden. Zanzibar was left on 

 28th June, 1886, Cape Gardafui was passed on 5th July, and 

 Aden reached on nth July, 1886. The season was therefore 

 that of the strongest south-east trade wind in the southern 

 part and of the south-west monsoon in the northern part of 

 the Indian Ocean. Captain Hoffmann kept as close to the 

 coast as possible, chiefly with a view of checking and correcting 

 the sailing direction for this little-frequented coast, but also 

 in order to test the view which he held that the inshore passage 

 at this season was not so risky as was commonly held. He 

 found this view completely justified, both wind and sea being 

 much less and more uniform. The daily epitome of weather 

 during the few days spent on this coast was sea-breeze from 

 midday to midnight, fresh enough to enable progress to be 

 made under steam and sail, then a light land-breeze till 8 A.M., 

 and in the forenoon calm. The sea-breeze would be a fair 

 wind for the "Mowe," and its lightness may be gauged by the 

 fact that the sails alone were not thought sufficient for making 

 passage, especially when assisted by the very strong northerly 

 current. On one day 240 miles were made good, although 

 the highest speed logged was only 6-5 knots. This gives an 

 average of 3-5 knots per hour in the twenty-four hours; and, 

 as all these currents are affected by tidal influences, its maximum 

 speed may have been much greater. Captain Hoffmann 1 

 says: 



1 Ann. Hydr. (1886), xiv. pp. 395 and 500. 



