PREFACE. 5a 
tions of the Lords Commissioners of the Admiralty, founded 
upon the recommendations of a committee of the Royal Soci- 
ety, were followed so far as circumstances would permit. We 
always kept in view that to explore the conditions of the deep 
sea was the primary object of our mission, and throughout the 
voyage we took every possible opportunity of making a deep- 
sea observation. We dredged from time to time in shallow 
water in the most remote regions, and we have in this way 
acquired many undescribed animal forms; and collections of 
land animals and plants were likewise made on every availa- 
ble occasion; but I rather discouraged such work, which in 
our case could only be done imperfectly, if it seemed likely to 
divert our attention from our special object. 
Between our departure from Sheerness on the 7th of Decem- 
ber, 1872, and our arrival at Spithead on the 24th of May, 1876, 
we traversed a distance of 68,890 nautical miles, and at inter- 
vals, as nearly uniform as possible, we established 362 observing 
stations. 
At each of these stations the following observations were 
made, so far as circumstances would permit. The position of 
the station having been ascertained— 
1. The exact depth was determined. 
2. A sample of the bottom averaging from 1 oz. to 1 Ib. in 
weight was recovered by means of the sounding instrument, 
which was provided with a tube and disengaging weights. 
3. A sample of the bottom-water was procured for physical 
and chemical examination. 
4. The bottom temperature was determined by a registering 
thermometer. 
5. At most stations a fair sample of the bottom fauna was 
procured by means of the dredge or trawl. 
6. At most stations the fauna of the surface and of interme- 
