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cation of a heavy gouge to aid in bringing up specimens of the 
bottom. 
The recording apparatus is a modification of the paying-out 
apparatus used for laying deep-sea telegraph cables. 
The protractors are diagonal telescopes mounted on bars 
revolving on vertical axes, and having fiducial edges radiating 
from the centres of the axes. 
One protractor is placed at each extremity of the base on a 
horizontal table, on which is strained a sheet of drawing paper; 
the telescopes are first collimated with each other, and then a 
line is drawn by the fiducial edges on each sheet of paper; the 
boat with the surrounding apparatus is followed by the two 
observers at the protractors, and when a signal is given, a line 
is ruled and numbered by each observer ; finally the two papers 
are placed so as to have the lines of collimation in coincidence 
and the centres at the scale distances apart; then by looking 
through the papers and pricking the intersections of the cor- 
responding lines, the positions of the boat are laid down on two 
maps. 
In practice this is all done easily, and no particular skill 
is needed in the observers with the protractors. 
The results obtained shewed that the bottoms of these lakes . 
are comparatively flat, the greatest depths being reached at a 
short distance from the shore on the cross section, and occurring 
also nearer to the upper end of the lake than to the lower: the 
forms of the bottoms correspond in a remarkable manner with 
the set that would be given to glaciers descending into the 
hollows in which the lakes lie; and Mr Kingsley believed them 
to have been formed by the action of glaciers during the ex- 
treme cold or penultimate glacier epoch; because in one case, 
that of Llyn Cawlyd, the lake lies almost on a watershed, 
where no glacier could now form, but which was a depression 
forming a lateral outflow from the great glacier that at one 
time filled the whole hollow between the Glydyrs and Carnedds; 
