PHYSICAL INVESTIGATIONS OFF THE NEW ENGLAND COAST. 395 
directly from the reel (containiug 1,000 fathoms) to a sheave ruuiiing between two 
standards located on the schooner’s rail. This sheave had a diameter of 22.8 inches, 
and one revolution thus corresponded to 1 fathom of wire ; attached to the axis of the 
sheave was a register which indicated the number of fathoms of wire out. 
The wire passed from the registering sheave to a small sheave on the end of a davit, 
extending over the side of the vessel. The davit arm was attached to the standards 
containing the registering sheave by a pintle, which allowed the davit to be swung 
inboard or outboard, and also by a joint which permitted the davit to be raised or low- 
ered, thus regulating the distance of the wire from the side of the ship. The outer 
end of the davit was hung from the main cross-trees by an accumulator consisting of 
two steel springs, one resisting a pressure of 300 pounds and the other 600 pounds, 
which served to relieve the strain upon the wire caused by the motion of the vessel. 
Just abaft the standards of the davit, upon the rail of the vessel, a platform was 
built, where an observer stood to fasten the instruments upon the cable as it descended 
and take them from it and read their indications as it was reeled in. 
The apparatus was all placed upon the starboard quarter-deck of the vessel. 
I METEOROLOGICAL INSTRUMENTS. 
: (1) Barometer . — The barometer used was of the ordinary marine form with the 
I lower portion of the tube of a small diameter. It was graduated to read 0.002 inch. 
During the summer the instrument hung in the laboratory of the schooner, the cistern 
of the barometer being on a level with the water line of the vessel about midships. 
(2) Thermometers. — {a) The thermometer used for the observation of the tem- 
perature of the air was au instrument constructed with the greatest care. It was 
placed upon an ivory frame, which was mounted so as to keep the instrument at a 
distance of inches from the board upon which it was hung. The position of the 
thermometer was horizontal. 
(6) The temperature of the surface water was obtained by drawing a pail of water 
from over the side of the vessel, placing it in the shade, and allowing the thermometer 
to remain in the water from two to live minutes, dependent upon circumstances. Dur- 
ing the trip we used the Wilder protected thermometers with brass scale and copper 
case. Our set at first consisted of three of these thermometers, one of which, No. 
6795, was lost early in the trip. 
(c) Dew-point thermometers : This set consisted of two thermometers mounted 
upon the same metal frame, one of which was supplied with water from a glass tube 
fastened to the back of the frame, as in Mason’s hygrometer. 
(d) The maximum and minimum thermometers were of the ordinary construction, 
the maximum being a mercurial thermometer in which a small part of the mercurial 
column was separated from the rest and served as an index. The minimum was an 
alcohol thermometer with a metallic index. In addition to these a Six’s maximum and 
minimum thermometer was also used, but its indications were very unsatisfactory. 
(e) Observations upon the rainfall and evaporation were made by means of a 
Symons rain gauge and an evaporating dish. The rain gauge had a 6-iuch collecting 
funnel which led into a bottle strongly protected by a zinc casing, into which the funnel 
fitted as a cover. The evaporation dish was also 6 inches in diameter. It was 2 inches 
deep and was covered by a coarse wire network. These instruments were exposed 
at the stern of the vessel just above the gig. 
