By an unfortunate oversight in Bulletin Mus. Comp. Zoól., Vol. V., 
No. 3, the paper of Sir William Thomson was omitted. It is as fol- 
lows, and should have been inserted after the introductory remarks 
in the first paragraph of the first page ending “I quote his own 
words to explain its action ” : — 
* A measured resistance is applied systematically to the wheel, always more 
than enough to balance the weight of wire out. The only failure in deep-sea 
soundings with piano-forte wire, hitherto made, has been owing to neglect 
of this essential condition. "The rule adopted in practice is to apply resistance, 
always exceeding by ten pounds the weight of the wire out. Then the sinker 
being 34 pounds, we have 24 pounds weight left for a moving force. That, I 
have found, is amply sufficient to give a very rapid descent, — a descent so 
rapid that in the course of half an hour or fifty minutes the bottom will be 
reached at a depth of 2,000 or 3,000 fathoms, The person in charge watches 
a counter, and for every 250 fathoms (that is, every 250 turns of the wheel) he 
adds such weight to the brake-cord as shalladd 3 pounds to the force with 
which the sounding-wheel resists the egress of the wire. That makes 12 
pounds added to the brake resistance for every 1,000 fathoms of wire run 
out. The weight of every 1,000 fathoms of the wire in the air is 144 pounds. 
In water, therefore, the weight is about 12 pounds ; so that, if the weight is 
added at the rate I have indicated, the rule stated will be fulfilled. So it is 
arranged that when the 34 pounds weight reaches the bottom, instead of there 
being a pull, or a moving force, of 24 pounds on the wire tending to draw it 
through the water, there will suddenly come to be a resistance of 10 pounds 
against its motion. A slight running on of the wheel, — one turn at the most, 
— and the motion is stopped." 
