TWENTY-FIFTH ANNUAL REPORT 139 



Refrigeration of Fresh Water. — It has always been neces- 

 sary to operate a refrigerating plant at the Aquarium during the 

 summer months, for the benefit of northern species of fishes. It 

 is kept in operation as long as the water temperature remains 

 above sixty degrees Fahrenheit. Since 1917 it has been possible 

 to shorten the period during which refrigeration is required, as 

 may be seen by an examination of the following table : 



RECORD OF ANNUAL PERIOD OF OPERATION OF THE REFRIGERATING 

 PLANT OF THE NEW YORK AQUARIUM, FROM 1907 TO 1920.* 



Average days, 163 



Average days, 128 



OBITUARY 



Mr. W. I. DeNyse, who had been connected with the Aquarium 

 in the capacity of Aquarist since its opening on December 10, 

 1896, died January 1, 1921, at the age of 61 years. 



Respectfully submitted, 



Chas. Haskins Townsend, 



Director. 



''From records kept by Mr. James C. Moore, Chief Engineer. 



