I04 



NA TURE 



\Nov. 30, 1876 



a right or left hole passes, the corresponding pricker falls 

 into the hole, and in doing so lifts a spring through the 

 opening / or /' into the rim of the revolving wheel O o'. 

 The spring being caught in the rim of the wheel is obliged 

 to remain there until the wheel makes one complete 

 revolution, and the opening in the rim returns to free it. 

 The wheel makes one revolution while one space passes 

 the pricker. When the spring is lifted into the rim of 

 the wheel it makes connection between the battery and 

 another set of springs. The latter set of springs are 

 acted on by a double cam, ( l', which is conntcted with 

 the same shaft as O o', and revolves with it. During one 

 revolution this double cam by means of the second set of 

 springs sends first one current from the battery into the 

 cable, and immediately afterwards a second current of 

 the opposite name and of rather shorter duration. The 

 first current is the signal and the second is the curb 

 current. If a left-hand hole in the punched paper passes, 

 and the corresponding pricker falls into it, a positive 

 current will be sent first, followed by a negative current, 

 but if a right-hand hole passes, the first current will be 

 negative, followed by a positive one. 



Fig. 6 shows the appearance of the punched paper 

 when it is prepared for the Automatic Sender. The 

 specimen represents the signal "understand" and the 

 fir^t seven letters of the alphabet. 



ON THE CONDITIONS OF THE ANTARCTIC^ 



MY principal object in this evening's lecture is to 

 direct your attention to some of the peculiarities in 

 the physical conditions of the Antarctic regions, and to 

 put you in a better position to contrast these with the 

 more generally known phenomena of the Arctic ; and it 

 seems specially appropriate to allow our thoughts to 

 travel for an hour towards that other fortress of the Ice 

 King, a fortress apparently even more hopelessly im- 

 pregnable, now whde the pulse of the nation is st;ll 

 throbbing in sympathy with the brave little band who 

 have just added another chapter to a long and terrible 

 record of daring and self-sacrifice, and have succeeded in 

 the face of almost unparalleled hardships in once more 

 planting the Union-Jack nearest to the North Pole. The 

 propriety is all the greater seeing that Capt. Nares, the 

 gallant leader of the northern explorers, is also the last 

 of the few navigators who have crossed the Antarctic 

 Circle. 



I will first of all then give you a brief sketch of our 

 Antarctic experiences in the Challenger, and then go on 

 to consider what may be the most prolaable explanation 

 of some of the most striking of the appearances which we 

 observed. 



After spending about a month at Kerguelen Island, 

 making meteorological and other observations, and se- 

 lecting a suitable spot for the observation of the transit 

 of Venus by the English astronomical party in the follow- 

 ing season, the Challenger left Christmas Harbour on 

 January 31, 1874, and on February 6 we reached the deso- 

 late little group of the Heard Islands, and on the 7th 

 continued our course southwards. 



Early on the morning of the nth a large iceberg was 

 observed bearing south-south-east about six miles off. The 

 berg was table-shaped, the top perfectly flat and covered 

 with a dazzling layer of snow. The perpendicular ice-cliffs 

 bounding it were of a delicate pale blue, apparently per- 

 fectly clear, with some caves and slight recesses, where 

 the blue was of a deeper shade. The height of the berg 

 above the sea was 219 feet, and its extreme length by 

 angular measurement was 2,202 feet ; so that, supposing 

 it'to be symmetrical in shape, the contour of the visible 

 portion being continued downwards, its depth below the 



' The substance of a lecture by Sir C. Wyville Thomson, K. R.S., delivered 

 in the City Hall, (.lasgow. on November 23, under the atrangements of the 

 Glasgow Science Lecture Association. 



water may probably have been about 1,500 to i,8oo feet. 

 In the afternoon Lord George Campbell observed during 

 his watch a large piece come off the side, dashing up the 

 spray, and we afterwards saw a quantity of fragments 

 floating off". 



The 1 2th was misty, with a breeze force = 3-4 from 

 the north-west by west. Many icebergs came in sight 

 from time to time and quickly became obscured in the 

 mist. The position of the ship at noon was lat. 62° 36' S., 

 long. 80° 4' E. 



Towards evening we passed close to a very beautiful 

 iceberg. One part of it was rounded and irregular in 

 form, putting us in mind of the outline of the Sphinx, 

 and another portion, separated from the first by a fissure, 

 the sea dashing through between them, was like a frag- 

 ment of a colossal cornice. As the sun sank the ice took 

 a most lovely pink or mauve tint, and when we came 

 close up to the berg it showed out veined in a wonderful 

 way with lines of deep cobalt- blue. The ice was perfectly 

 pure and clear. The bergs which we were passing at this 

 time seemed to be breaking up very rapidly ; some large 

 fragments had been detached from this one shortly before 

 we reached it, for a quantity of debris was floating at a 

 little distance. The pieces washing about in the water 

 very soon lose their edges and angles, and get rounded, 

 and shortly disappear. 



The 13th was a fine day, with a light wind from the 

 north-north-east and occasional snow showers. There 

 were some large tabular icebergs along the southern 

 horizon. In the afternoon we passed close to a beautiful 

 berg, very irregular in form, all the curves and shadows 

 of a most splendid blue. The lower portion of the side 

 of the iceberg next us formed a long steep slope into the 

 water, and up this slope the surf ran with every heave of 

 the swell, taking in its course the glorious blue of the ice 

 and ending at the top of the glacis in a line of glittering 

 foam. 



The evening fell grey and slightly misty, with a number 

 of icebergs looming through the mist. One or two of us 

 were standing on the bridge about midnight looking at 

 what seemed to be a low bank of white fog coming down 

 upon us, when all at once a universal grating and rasping 

 sound and sensation seemed to pervade the ship, arid 

 looking over the side we found that instead of saiUng in 

 open water we had passed into the edge of the pack, and 

 as far as the eye could reach to the eastward the sea was 

 closely covered with blocks of ice of all sizes up to six or 

 seven feet in length among which the ship ground her 

 way. A cold-looking moon struggled faintly through the 

 cloud and mist and showed the pack vaguely for a mile or 

 so ahead, covered with a light fog through which we could 

 just see several icebergs looming right ahead of us and on 

 either bow, and the masses of ice becoming larger and 

 forming a closer pack as we passed ^inwards from tb« 

 outer edge. 



It was a wonderful and in a certain sense a beautiful 

 sight, but one which would certainly require for its full 

 enjoyment very fine weather such, as we had, or a spe- 

 cially strengthened ship. 



The necessary orders were given, and we veered roimd 

 and slowly passed out of the pack and into open water ; 

 and we hung about beyond the line of wash-ice for the 

 short Antarctic night. 



On the following morning there were icebergs all round 

 us, some of them of very fine forms. One which we saw 

 all day on the port quarter was gable- shaped with a 

 glorious blue Gothic arch in the centre, and a separate 

 spire over 200 feet high. It was like a gorgeous floating 

 cathedral built of sapphire set in frosted silver. 



All day the pack could be seen from the deck stretching 

 away to the east and south as far as the eye could reach, 

 a mass of rugged gUttering blocks one piled on the top of 

 another. The ice-blink, a beautiful and characteristic 

 phenomenon, was very marked above the pack — a clear 



y 



