AIR TEMPERATURE 
INSTRUMENTS AND METHODS 
Thermometers 
The only mercurial thermometer used for obtaining 
air temperatures during the cruise of the Carnegie was 
contained in the Assmann aspiration psychrometer. 
The dry-bulb tube (P.T.R. No. 2451-1928), mounted in 
the instrument screen, was a standard instrument and 
needed no corrections throughout the ranges of temper- 
ature encountered on the cruise. The ASsmann psy- 
chrometer was read daily at noon (GMT), and the dry- 
bulb readings were used primarily for correcting the 
air-temperature records ofthe recording thermometers. 
Meteorological Screen 
The instrument screen was of the Stevenson type 
(fig. 11) and was mounted on the quarter-deck amid- 
ships, just forward of the wheel with the center of the 
screen 6.4 meters from the counter rail, 3.2 meters aft 
of the engine-room hatch, 3.7 meters from each side of 
the rail, and 3.7 meters above load water line. 
Previous investigations have shown that the heating 
and cooling of a vessel’s surface makes it very difficult 
to obtain accurate air-temperature readings within an 
ordinary thermometer screen on board. Lutgens [20] 
‘thus found errors up to 7° in the meteorological observa- 
tions taken on board the Pangani, and Spinnangr [21], in 
studying the temperature measurements during a voyage 
on the S. S. Bergensfjord, found errors of 1° to 2°. 
Other investigators have reported similar results. 
These acknowledged errors have led Russeltvedt [22] 
to suggest that two or more screens mounted on oppo- 
site sides of the vessel are necessary for accurate air- 
temperature measurements. 
No doubt the uncorrected air-temperature observa- 
tions on board the Carnegie are highly errcneous owing 
to the fact that only one instrument screen was usedand 
this was placed far from the rail. As will be explained, 
however, by using temperature measurements obtained 
at considerable heights above the deck and observing the 
diurnal variations between these and the deck observa- 
tions, it has been possible to apply corrections to the 
deck temperatures and to obtain results which shouldbe 
reasonably accurate. 
Thermograph 
The Negretti-Zambra capillary ventilating record- 
ing psychrometer, which will be discussed in greater 
detail in the chapter on humidity, was housed in the 
Stevenson screen and the recorded dry-bulb readings 
used in the temperature studies. This instrument was 
calibrated daily at noon against the Assmann psychrom- 
eter. 
From time to time difficulty was experienced with 
the recording pens; the pen points had to be replaced at 
frequent intervals as the constant vibration of the appa- 
ratus soon wore them smooth. When the recording ap- 
paratus was first mounted in the Stevenson screen, the 
pens were adjusted to give true readings directly on the 
thermogram, but in regions of high humidity it was 
found that the wet- and dry-bulb pens would come into 
contact with one another. To obviate this difficulty 
13 
the wet-bulb pen was later lowered one degree on the 
trace and an “‘offset’’ correction applied. In foggy or 
rainy weather the thermogram paper absorbed so much 
moisture that the traces became blurred. 
The traces of the Negretti-Zambra instrument were 
scaled at each hour, local mean time, and corrected 
from the Assmann readings. These hourly temperature 
data appear in appendix III, table 78. 
Hartmann and Braun 
Electrical-Resistance Thermographs 
While the Carnegie was in Hamburg (June 22 to July 7, 
1928) the firm of Hartmann and Braun installed three 
pairs of wet- and dry-bulb electrical-resistance ther- 
mometers at various heights above the deck (fig. 2). It 
was intended that these be used to record lapse rates 
from deck to crosstrees and masthead. The first pair of 
thermal elements was located in the Stevenson screenon 
the quarter-deck, 3.6 meters above sea leve!. The sec- 
ond pair was housed in a small naturally ventilated 
screen, 1.4 meters above the crosstrees on the mainmast 
and 21.9 meters above sea level. The third pair was at- 
tached near the main truck in a similar screen, 34.6 
meters above load water line. From each of these ther- 
mal elements a single-strand, two-conductor cable led 
to the multiple recording apparatus in the control room 
on the quarter-deck. 
The electrical recording apparatus had a separate 
pointer and distinctively colored ribbon for each ther- 
mometer. On the Carnegie, the pointers corresponding 
to the pairs of thermometers were “‘offset’’ on the rec- 
ord sheet so that the elements in the deck screen record- 
ed 3° too high, those at the crosstrees 1°5 too high, and 
those at the masthead according to the zero scale of the 
sheet. This procedure was followed in order to prevent 
the dots on the thermogram from becoming too confused 
for reading. 
Some difficulty was experienced because of blotting 
and blurring of the trace when new ribbons were first 
installed. The clockwork of the apparatus was excellent, 
and it was seldom necessary to reset the thermogram to 
the proper time mark. 
Corrosion and the constant working of the rigging 
caused frequent breaks in the cable running from the 
masthead and crosstrees. This was largely due to the 
fact that the cables were attached directly to the hemp 
rigging. Doubtless this difficulty would have been elim- 
inated if suitable conduits had been used. Temporary 
repairs to the cable were not made at sea when these 
breaks occurred, because of the probability of changing 
the resistance in the electrical circuit from a constant 
to variable. In each case, as soon as suitable cable 
could be obtained, an entire new length was installed and 
the resistance again measured before the apparatus was 
put into operation. 
These thermometers were calibrated from time to 
time against readings of the Assmann psychrometer; 
those in the Stevenson screen were compared daily. 
It is evident that the value of the recorded tempera- 
tures depends on the efficiency of the ventilation of the 
screens, which in turn is a function of the wind speedand 
direction. Unfortunately, all wind records of the Carne- 
gie were lost when the vessel was destroyed, and thus no 
