The 65 c.m. Barr and Stroud rangefinder was useful in giving the distances to lay off the bearings of the various points in survey work and, with vertical angles, obtaining the heights of peaks, islands and icebergs.
The larger 4 feet 6 inches rangefinder was virtually useless, as we could only use it in a completely land-locked harbour.
The naval wireless set, rotary spark transmission and continuous wave, lent us by the Admiralty, was particularly useful in giving us G.M.T., and so correct longitude. Our reception was very good; we received, when 68° 49´ S., time signals from Rio Janeiro at a distance of 3,206 miles. We heard messages from ’Frisco at a distance of about 8,000 miles while in 65° S. lat., and later in lat. 50° S. received time signals from Nauen, Germany, 9,000 miles distant. The latitude appeared to be a governing factor, as S. of 50° S. lat. we experienced very bad atmospherics, while S. of 55° there appeared to be an almost constant roar in the receivers, making it impossible to read signals, although they could be often heard. There may have been more silent intervals than appeared, as we only had one operator, and being busy on ship’s work he only listened for half an hour at the appointed time for the signals.
The greatest distance that we transmitted signals was about 400 miles in Cape Colony; normally we could get 200 miles. The earth was rather a problem; being a wooden ship, we fastened large copper sheets to the ship under water, but they were repeatedly torn loose when forcing our way through the ice.
The wireless telephone lent by Marconi’s worked very well. We spoke for a distance of 100 miles with it approaching Rio, and it was made evident that on any expedition it would be very useful, its only drawback being the loud roar made by the engine, which could be silenced considerably.
A new large-scale chart was made of St. Paul Rocks and surrounding submarine plateau contained within the hundred-fathom line on a scale of 200 feet to the inch, the Admiralty Chart 388 being on a scale of 2,029 feet to the inch.
From their small size (the largest being 380 feet by 180 feet) and the probability that erosion is taking place, it is doubtful if they can ever be used for an aerial station or any other purpose except a lighthouse or wireless meteorological and directional station.
At South Georgia we carried out series of over two hundred soundings W., S.W., N. and E. of South Georgia, discovering several banks, one with apparently a fairly clear bottom for trawling in from 50 to 100 fathoms from 10 to 30 miles offshore to the N.W., but this area requires more examination than we had time to give it. All the other banks had very irregular bottoms.
We found no indication of a bank at a greater distance to the N.E., as has been reported, but the 200-fathom line is much farther off to the S.W. than was expected.
From whalers’ reports and our soundings it would appear that there is a more or less continuous bank to the N. and N.E. of and parallel to the island, with deeper water forming a submarine valley between. With a limited examination, we found the bottom to consist mainly of a dark grey sand, gravel and stones. The whalers report that these banks swarm with an incredible number of very good eating fish, so easily caught that they can be “jigged” up with no bait, but a bit of bright metal on the hook.