ADDENDA. 351 



Page 172, § 472, 



Commander Eodgers, while commanding the North Pacific Sur- 

 veying Expedition, passed up into the Arctic Ocean through Behr- 

 ing's Strait. He has had the kindness to furnish me with his olb- 

 servations for temperature and specific gravity of the water at the 

 surface of that ocean, midway, and at the bottom. These observa- 

 tions throw light from a new quarter upon what has already been 

 said concerning an open water in the Arctic Ocean. They are of 

 exceeding interest and value in that light. In all the experiments 

 there, he invariably found warm and light water at the top, cold 

 water in the middle, and hot and heavy water at the bottom. 



Observations on Specific Gravity and Deep-Sea Temperatcre (U. S. Ship 



ViNCENNES, Commander John Eodgers, Commanding). 



August 13, 1855.— Lat. 72° 02' 27" N., long. 174° 37' 00" "W. 



Sea smooth; temjierature of air, 45.2°. 



Wateb in Cylindeb. 



1st Trial.- 



2d Trial. 



Depth, 40 fathoms. 



* Within 2 feet of tlie bottom. 



August 14th.— Lat. 71° 21' 30" K, long. 175° 22' 00" W, 

 Sea smooth; temperature of air, 45°. 



Watee. 



Starch, 10 parts ; iodide of potassium, 20 parts ; water, 400 parts. Mix, dip pa- 

 per in the mixture, and dry. Preserve the paper, folded, in a close vessel. For 

 use, a scale of colors should be prepared, with which to compare the deepness of the 

 colors produced by ozone. When making the observation, the test paper should be 

 placed where the air has free access. 



Diseases are thought to be more or less prevalent according to the abundance of 

 ozone in the air. The medical staff of the navy, in their cruises abroad, have fine 

 opportunities of throwing light on this subject. 



