183 



thread. Another disturbing effect was due to the unfavourable climatic conditions. On several occasions, 

 for example after a silver thaw, i.e., rain falling with a temperature below the freezing-point and 

 congealing as it fell, it would take over an hour to get into the hut, which would be plastered on the 

 weather side with solid ice over an inch thick. This had to be carefully cut away from the door and 

 windows, so as to avoid injuring the woodwork. Inside the hut further difficulties had to be overcome. 

 The instrument would often be found encrusted with ice spicules requiring thawing out. This effected, 

 and everything in working order, the rattling of torrents of drift on the roof and sides was at times so 

 great that the beats of the chronometer about two feet off could not be heard, thus making the time of 

 vibration unsatisfactory, while in the deflection series the mirrors would become covered with ice resulting 

 from the freezing of the moisture generated by the observer's breath. Frequently from one of these 

 causes the first or second portion of the observations -could not be completed. 



During the winter Dr. W. S. BRUCE, leader of the expedition, gave me every opportunity for the 

 prosecution of magnetic work, and that more was not effected was largely due to the causes already 

 referred to. In September, October and November sledge parties were in the field, and a good deal of my 

 time was occupied in the routine associated with the taking of the hourly meteorological observations, 

 which precluded any systematic series of magnetic measurements. On November 27, immediately after 

 the break-up of the ice, the " Scotia " left for Buenos Aires to refit, leaving a party of six to continue the 

 work during the summer. The summer party were accommodated in a stone house, situated 140 yards 

 west of the observatory, so that it was now possible, owing to its proximity and to the better weather, to 

 make a more extended series of observations, which include hourly readings of declination on 20 days. 

 In taking this set, I was ably assisted by Mr. WILLIAM MARTIN, General Scientific Assistant. On the 

 return of the "Scotia," on February 14, the station was taken over by the Argentine Meteorological 

 Office, and the meteorological and magnetic observations were carried on under my direction till the end 

 of 1904, the work being still continued under the auspices of the Argentine Government. 



The South Orkneys are a small group of islands situated between 60 and 61 S., and 44 and 47 W., 

 about 700 miles S.E. by E. of the Falkland Islands, and about 250 miles E. of the nearest islands of the 

 South Shetlands. The group consists of two large islands Coronation and Laurie Island and numerous 

 smaller ones. The two large islands are separated from one another by two small islands and Washington 

 and Leethwaite Straits. Laurie Island, although its greatest length is in an E.N.E. and W.S.W. direction, 

 consists of numerous peninsulas and steep and lofty mountain ranges running in a general N.W. and S.E. 

 direction. The length of this island is about 12 miles, its maximum breadth 6 miles, and its area fully 

 30 square miles. Coronation Island is 35 miles long, but as no detailed survey has been made, particulars 

 regarding its area cannot be given. The central cairn is approximately in latitude 60 43' 42'' S. and 

 longitude 44 38' 33" W., this cairn being 79 feet west of Copeland Observatory. 



The islands, it may be said, are largely composed of fine-grained greywacke of a bluish or greenish 

 colour. Varieties of the greywacke are found, such as conglomerates, slate, and patches showing gneissic 

 banding and folding. In one situation regular beds of shale were found alternating with layers of grey- 

 waeke. The islands are thus composed of sedimentary rocks, and nothing was found to produce local 

 disturbances in the magnetic elements through the presence of iron or other minerals.* It may be 

 remarked that the islands rise very suddenly out of deep water of about 2000 fathoms, and that the 

 bathymetric gradient is steeper on the north than on the south side of the islands. (See W. S. BRUCE 

 " Bathymetrical Survey of South Atlantic Ocean and Weddell Sea," 'Scot. Geog. Mag.,' August, 1905.) 



See "On the Graptolite-bearing Rocks of the South Orkneys," by J. H. HABVEY PIRIE, B.Sc., 'Proc Roy. Soc., Edin.,' 

 vol. xxv., pp. 463-470. 



