SURVEY EQUIPMENT 215 



Observations on hydrogen-ion concentration were made colorimetrically owing to the 

 impossibihty of setting up dehcate electrical apparatus on board ship. Special sets of 

 sealed standard tubes, made up from Palitzsch's buffer solutions^ of borax and boric acid 

 and a 0-02 per cent solution of phenol red as indicator, were supplied by British Drug 

 Houses, Ltd., and renewed several times during the commission. These had a range 

 of pH 6-8 to 8-4, ascending by 0-05. A thymol blue range was also used, giving a range 

 of /)H 8-0 to 9-0. The method employed in determining the pH value of a sample was 

 to measure out 10 c.c. from an accurate pipette into a test tube of the same internal 

 diameter as the tubes of the standard range. A fixed quantity of indicator (varying 

 with each set of standard tubes) was then added, and the tube compared with the 

 standards by the light of a " daylight " electric bulb shining indirectly from behind, with 

 the rest of the laboratory in darkness. 



SURVEY EQUIPMENT 



Existing charts of the Dependencies of the Falkland Islands are deficient in many 

 respects, and with a view to their improvement the services of a trained surveyor were 

 placed at the disposal of the Discovery Committee by the Admiralty. This officer, 

 Lieut-Comdr. J. M. Chaplin, R.N., was Navigator and (later) Chief Officer on the 

 'Discovery'. 



Opportunities for hydrographic survey were necessarily limited by the fact that the 

 vessel was almost continuously engaged in work on hydrography and plankton, but 

 during the last commission useful work was done at various times in the 'Discovery', 

 and on a number of occasions it was found possible to free the survey officer from his 

 duties on board, thus enabling him to carry out coastal surveys in the Dependencies. 



In South Georgia particular attention was paid to harbours, hitherto uncharted, 

 which are habitually used by vessels of the whaling fleet, and since these are for the 

 most part uninhabited it became necessary to establish temporary camps. Small tents, 

 sleeping bags, stoves and other gear from the ship's sledging equipment were used in 

 these operations, and provisions were worked out with a margin of at least 30 per cent 

 above the full supply for the agreed period, in view of possible difficulties in aff'ording 

 relief. The personnel of these survey expeditions consisted of the survey officer, a cadet 

 and one seaman, accompanied sometimes by the ship's doctor and by a member of the 

 scientific staff. A light pulling boat — a Norwegian pram — was taken, fitted with a small 

 Lucas sounding machine, together with an 8 ft. tide pole and poles and flags for beacons 

 and marks. 



The surveying instruments were supplied almost entirely by the Admiralty and most 

 of them do not require description. We are indebted to Lieut. -Comdr. Chaplin lor the 

 following notes: 



Of the theodolites the Zeiss 3 inch transit theodolite no. i, with automatic mean reading, was 

 used most extensively: it was found to possess great accuracy, and its light weight and compactness 

 were important factors. Owing to the friable nature of the rock in South Georgia no attempt was 



1 W. Mansfield Clark, Determinatioti of Hydrogen-iotis, pp. 115, 117, Baltimore, 1923. 



