TWENTY-FIFTH ANNUAL REPORT 137 



to the exhibition tanks to avoid losses. All fishes left in the well 

 of the boat while the vessel is moored behind the Aquarium die 

 within two or three days. The low salinity of the harbor water, 

 less than halt that of the open sea, is shown in the following 

 table : 



RECORD OF MONTHLY MEAN TEMPERATURES AND SPECIFIC 



GRAVITIES OF THE WATER OF NEW YORK HARBOR AT 



THE BATTERY, DURING THE YEAR 1920* 



Temperature. Specific Gravity. 



January : 39° 1.014 



February 36° 1.015 



March 38° 1.011 



April 42° 1.007 



May 49° 1.011 



June 58° 1.012 



July 65° 1.012 



August 68° 1.013 



September 69° 1.013 



October 63° 1.013 



November 56° 1.013 



December 49° 1.010 



The Supply of Fresh Water. — The following table of water 

 temperatures, which has been prepared from daily records made 

 at the Aquarium, is published with a view to convenient refer- 

 ence. The water supply of the City was increased and improved 

 in 1917 by the addition of water from the Catskill Mountains. 



An examination of the table indicates that the water flowing 

 into the Aquarium since that time has a temperature somewhat 

 lower in summer and higher in winter than was formerly the 

 case. The greater equability is probably due to the fact that the 

 temperature of the naturally cooler mountain water is modified 

 by flowing a much greater distance underground. For the pur- 

 poses of the Aquarium the greater equability is desirable. 



*From daily observations made at the New York Aquarium by Mr. 

 W. I. DeNyse. Specific gravity observations were made with the samples 

 of water brought to a temperature of 60"^ Fahr. 



