APPARATUS AND APPLIANCES USED. 
53 
(Fig. 8) of 1 cwt. is attached to keep it perpendicular, 
and immediately above a thermometer is placed ; the 
line is then eased out to the first 100 fathoms, when 
a second thermometer is secured, and the line low- 
ered to 200 fathoms, a thermometer being placed at 
each 100-fathom mark until six or eight have been 
attached and the line run out to the required depth, 
say to 1500 fathoms ; it is now belayed and allowed 
to remain for a few minutes. The thermometers 
register the temperatures of the different 
depths at which they are submerged. The 
line is now hove in, and as each thermo- 
meter reaches the sounding platform, it is 
removed, and the results are carefully read 
off. The temperature is then taken from 
the surface to 700 fathoms in the same man- 
ner. Sometimes it is considered necessary 
to obtain temperatures at every 10 fathoms 
from the surface to 200 fathoms, and at 
every 50 fathoms to 600 or 700 fathoms; 
this, of course, considerably increases the time occu- 
pied in obtaining these observations. 
When the whole of the soundings and temperature 
observations have been obtained between any two 
places, a plan is drawn showing the section of the 
bottom and isothermal lines at different depths. 
For the purpose of dredging in deep water, three 
different-sized ropes are supplied, of 2, 2|-, and 
3 inches in circumference. Each rope is spliced so 
Fig. 8. 
