File:The crustacea of the plankton, July, 1894-Dec., 1896 (1897) (14588095829).jpg

Identifier: crustaceaofplank00birg (find matches)
Title: The crustacea of the plankton, July, 1894-Dec., 1896
Year: 1897 (1890s)
Authors: Birge, E. A. (Edward Asahel), 1851-1950
Subjects: Plankton
Publisher: (Madison : s.n.)
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
nts employed until July 27th, 1896, after which date a ther-mophone was used. The latter instrument has proved extremelyuseful and accurate. A full description of the instrument maybe found in Science, Vol. II. of 1895, page 639. As constructedfor my work, the instrument ranges from minus 5 to plus 30degrees C, each degree being graduated into fifths. There isno difficulty in reading the instrument to less than 0.1 degreeC, and its readings are exceedingly accurate, agreeing exactlywith those of a standard thermometer with which it has beenconstantly compared. Observations can be made very rapidly,the time of a single reading varying from one to one and a halfminutes, according to the amount of change of temperature-from the last reading. Tha temperature bottle contained about 1^ litres and had asmall neck. It was lowered to the desired depth; allowed to re-main from one to three minutes for the glass to acquire the tem-perature of the water; was then uncorked by a sudden jerk on the*
Text Appearing After Image:
00 «D 00 «D Temperatures. 287 line, and allowed to fill. It was then drawn rapidly to the sur-face and the temperature read by means^of a long-stemmed ther-mometer graduated to one-fifth of a degree. The time of rais-ing the bottle from the bottom of the lake was ordinarily aboutten seconds; and the small size of the opening prevented mix-ture of the upper water with that in the bottle. The tempera-ture of the water in the center of the bottle, which was meas-ured by the thermometer, did not change perceptibly during thetime required for the thermometer to set. The water from thelower part of the lake, however, was somewhat warmed by con-tact with the glass and the air in the bottle. This error wascarefully determined by comparison with the thermophone, andis about one-fifth of a degree C, when the difference betweensurface and bottom is about 10 degrees. Errors much more considerable than this occur with the useof the temperature bottle at the thermocline. In this regionthe tempera

Note About Images