2i6 DISCOVERY REPORTS 



made to obtain heights by theodolite except at sea level. The pocket aneroids were therefore most 

 useful for determining such heights and contours: the pocket sextant was also useful in similar 

 circumstances. 



The Dover compass was satisfactory, but was found after the first passage to have worn the pivot 

 flat through the constant rolling of the ship. 



The station pointers were the only instruments which gave any trouble. The brittleness of the 

 metal owing to cold and the hardening of the lubricant caused the arc attached to the legs of one 

 instrument to crack and rendered it useless until roughly repaired. 



One notable point was the long life of the silvering on all the sextant mirrors, due partly to the 

 very able work put into them and also partly to the dryness of the atmosphere. 



The chronometers deserve special mention. All of them without exception worked extra- 

 ordinarily satisfactorily and especially the chronometer marked C, which was taken on the first 

 camping expedition as an experiment. So far as could be seen the rate hardly varied at all. Every 

 precaution was taken to keep the temperature even, but it can be realized that under canvas the 

 temperature is bound to conform to that in the open air even through blankets and padded cases. 

 The chronometer was kept in the cooking tent and wound after cooking was finished in the morning, 

 i.e. when the tent was at its warmest. The rate was compared twice or three times with Nauen or 

 Lyons before leaving and again on returning, and was never found to have varied much : it was low 

 to begin with, in the region of o-i sec. per day, which of course was good. 



One point to be observed in this connection is that the W/T time signals in Schollaert Channel 

 and generally in the Palmer Archipelago were heard with greater strength and clearness than any- 

 where else. 



The tide readings were always a source of difficulty except in Leith Harbour, South Georgia, 

 where the pole was secured to a wooden wharf. In other harbours it was erected with its foot below 

 low-water mark and secured with stones tied round the foot and guys at suitable angles. Unfor- 

 tunately the male elephant seals in South Georgia seemed to have a dislike for it and frequently 

 we found the pole down in the morning, or waking up would find elephant seals in the act of pulling 

 it down. This did not affect the reduction for soundings but rendered the readings useless for calcu- 

 lating tidal data even if we had been able to get a sufficient number. 



During the course of the work it was never cold enough to make the use of the leather protection 

 on eyepieces and screws necessary. For the latter a pair of washleather gloves afTorded sufficient 

 protection to the fingers ; if leather was used it was found that it became dry and rendered round the 

 screws, thus increasing the awkwardness of working with cold fingers. 



The only improvement in the equipment that can be suggested is that a small W/T receiving set 

 should be taken on any future expedition which will involve camping away from the parent ship 

 or whaling station. 



LABORATORY METHODS 



On board ship laboratory accommodation is necessarily limited, and except in very 

 fine weather the rolling of the vessel renders any elaboration of technique impossible. 

 In intensive plankton work rapid disposal of the material is a first essential: the collec- 

 tions must be dealt with in bulk and even the most cursory examination of the material 

 must frequently be postponed. 



Sorting Collections. As a general rule the contents of i m., 70 cm. and 50 cm. 

 tow-nets were preserved in bulk, sometimes with the subtraction of specimens of un- 

 usual interest, and often (more particularly with the i m. nets) with the omission of 

 species, such as Salps, Eiiphansia and Eiithemisto, which by their abundance swelled 



