396 
BDLLETIN OF THE UNITED STATES FISH COMMISSION. 
(/) A solar radiation thermometer and a spirit minimum thermometer were also 
used in the open air. They were freely exposed to the sun and weather, suspended .; 
by cords in such a way as to be as free as possible from the elfect of the motion of the^' ? 
vessel, and were placed between the davits of the gig at its stern. I \ 
(g) Two portable air meters were also used, one with a S-inch opening and thel 
other with a 3-inch opening. These were used when the vessel was hove to upon a'f e 
station to observe the difierence in velocity of the wind upon the deck and at various | i! 
heights in the rigging. | ; 
(h) An ozonometer, consisting of a wire cage in which the prepared papers were?, 
exposed, was also utilized, but no observations were obtained which indicated the| ! 
presence of ozone in the air, with the exception of one single day, on which the| ? 
slightest tinge of purple was observed. This cage was exposed with the ' other k ' 
instruments at the stern of the vessel. fl: 
All the above instruments, with the exception of the barometer and those included S ? 
under the last four heads, were exposed in a case prepared especially for them, which | i 
served its purpose so well that a description of it is warranted and will be given 
below. The above instruments were all made by Mr. G. Tagliabue,- of 302 Pearl | | 
street. New York City, and he exerted himself to the utmost to secure great accuracy | 
in them, knowing the use to which they would be put. | 
Thermometer case. — This case was a strongly constructed box 3 feet long by 2 | | 
feet wide and 2J feet high at the front and back; it had a ridged top or roof, which t] 
served to shed the rain, making the central portion of the box 3 feet high. The lower'; : 
foot in height all around the box was closed, but the upper portion was composed of f " 
a lattice of louvre boards to allow a free circulation of the air. The box was secured j 
firmly to the deck just aft the cabin deck house. From the center of the ridge on the ; 
inside of the pent house a board was suspended by gimbals, and on this board, but I 
kept at a distance of 1^ inches from it by proper supports, the instruments were ii 
placed and secured by hooks. From the lower edge of the board directly below the 
gimbals a 10-pouud weight was suspended. This device secured the instruments in a 
practically horizontal position, because none of the movements of the vessel affected . 
them in the least. ■ ' 
Ii- ' 
INSTRUMENTS FOR SERIAL TEMPERATURE OBSERTATIONS. 7; ! 
k 
The instruments used for this work were made by Negretti & Zambra, and were r 
fitted with the Tanner deep-sea case and reversing apparatus. Our set consisted of 
twenty-five of these instruments, and they were placed in a strong pine box upon the Hi 
deck, where they would be convenient to the observer when wanted. The box was j | 
constructed like a trunk, with two trays and an open bottom space the same size as 
one of the trays. These trays were divided into spaces by a series of strips, across ii 
which a piece of canvas was stretched in such a manner that it served as a support |i: 
for the instruments. They were thus protected from all sudden jars, and were very 
accessible. In shallow water the upper tray, containing a water cup, a hydrometer, || 
a salinoineter cup with thermometer attached, and eight deep-sea thermometers (which | i; 
were all that were necessary), was exposed by opening the box. In the deep soundings, | i 
and when serial observations were made extending to 500 fathoms, where sixteen I 
thermometers and two water cups were used, the upper tray was removed when empty |ii 
