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.* 
Days in 
Year Started Stopped Operation 
1907 June 14 October 22, 130 
1908 May 25 November 4 164 | 
LGOOR eMiay a Ly October 8 145 
LTO May. ZL November 9 Is 
Oil May. a5 November 13 182 
1912 May 15 November 13 182 | 
tS June 12 November 14 156 | 
Average days, 163 
not4 May 23 October ol 162 
1915 May 20 November 8 173 
1916 May 29 November 13 169 / 
Loe es une 925 October 14 1A Ze 
1918 July 19 October 14 88 SAvotapel dave nts 
1919 May 31 November 6 160 otal am 
1920) June- 3 November 4 155 \ 
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. 
*Krom records kept by Mr. James C. Moore, Chief Engineer. 
