of Edinburgh, Session 1883-84, 
929 
which rise from a projecting horse-shoe-shaped piece beneath the 
lever. A hollow cylindrical weight shghtly belled out at the lower 
end is dropped down the line when the thermometer is to be 
reversed ; it falls on the forked lever, raises the pin, the upper end 
of the instrument gets an outward impulse from an india-rubber 
band slipped over the frame (a device of Mr Buchanan’s), and it 
rotates sharply, and is clamped by a brass spring. When several of 
these thermometers are used on one line, as is convenient in taking 
serial temperatures, the weight for the next lower instrument is 
hung by a wire to the groove in the toj) ; it helps to pull the ther- 
mometer over when released, then sliding down the line it strikes 
the lever of the next, reverses it, and despatches its weight. In 
this way any number of instruments may be used on one line. 
The ends of the lever forks are covered with india-rubber to diminish 
the shock, and the whole apparatus is constructed of brass, so that 
no galvanic action can be set up between any of its parts. 
The adaptation of the Negretti and Zambra thermometer to 
reverse by means of a weight slipped down the line is not new. 
Mr Rung, of the Meteorological Institute of Copenhagen, has 
invented a very simple method of doing this ; but, although his 
frame has worked admirably in his hands, it has the disadvantage 
of being constructed of wood. A simpler arrangement for the same 
purpose was employed on the United States ship “ Fish Hawk/’ but, 
from the account given of it, it seems to be inferior to the Scottish 
frame, in not clamping the instrument when reversed. The new 
thermometer was made before the description of either of these 
earlier forms was seen. It has been found to answer admirably, 
both in very shallow water and in depths up to 80 fathoms. 
The first set of observations was made hourly during a period of 
thirty-six hours, from 9 a.m. on June 17th to 9 p.m. on June 18th. 
The temperature of the air, of the water at the surface (by an 
ordinary thermometer), and at the bottom, were taken each time 
from the Ark, the floating laboratory of the Station. The mean 
temperatures (corrected) were as follows : — 
For 30 Hours Daylight. For 6 Hours Darkness. For 36 Hours. 
Air, . 
Water, surface, . 
Water, bottom, . 
58-7 
54*98 
54*60 
54*1 
54*88 
55*01 
54-97 
54*67 
57-9 
