April I, 1875] 



NATURE 



433 



sixtieth contact. The currents thus obtained (a small 

 battery only being used on the clock) are used to work a 

 relay from which three independent currents from other 

 batteries are derived. One acts upon the seconds magnet 

 of the chronograph for impress of seconds punctures on 

 the paper on the revolving cylinder. The omission of 

 one second in each minute marks with certainty the com- 

 mencement of the minute. Observations at all the funda- 

 mental instruments are registered on this cylinder, and 

 comparisons of clocks are thus entirely avoided. Another 

 current regulates a half-seconds chronometer on the eye- 

 end of the Great Equatoreal. The third current regu- 

 lates the pendulum of a half-seconds clock m the Great 

 Equatoreal Room, drives a tapper to make audible the 

 seconds of the clock, and drives also a galvanic chrono- 

 meter placed in the Computing Room for use in the daily 

 work of comparing and setting to time the mean solar 

 standard clock. The omission of one current in each 

 minute is unimportant as concerns the regulated chrono- 

 meter and clock, but not so as regards the chronometer 

 which is driven by the current. To accommodate the 

 chronometer to this state of things, its seconds wheel is 

 cut with fifty-nine teeth only, and its seconds circle on the 

 dial correspondingly divided into fifty-nine equal parts. 

 The restin" of the hand during one second, which takes 

 place at a particular division of the dial, consequent on 

 the loss of one current in each minute, is therefore com- 

 pensated for by this construction of the seconds wheel 

 and engraved dial plate. 



ARCTIC VEGETATION 



A FEW notes on the vegetation of the Arctic regions 

 may not be out of season at the present time. For 

 fuller details we may refer to Dr. Hooker's exhaustive 

 essay on the distribution of Arctic plants, published m 

 the Transactions of the Linnean Society, vol. xxui., 1S62. 

 Since the appearance of this article very little has been 

 added to our knowledge of Arctic vegetation, if we except 

 the flora of Spitzbergen. Several naturalists have since 

 visited the islands of this group, and about thirty addi- 

 tional species of flowering plants have been discovered 

 The greater part of these additions have been published 

 in the Journal of Botany, vol. ii. pp. 13° to '37 and 162 

 to 176, and vol. i., series 2, p. 152 ; but a few interesting 

 plants new to the group, collected by the Rev. Mr. Eaton, 

 and now in the Herbarium at Kew, do not appear to have 

 been published. With the exception of the shores 

 of Smith's Sound in North America, Spitzbergen is the 

 most northerly land yet trodden by the foot of restless 

 explorers and from its relative accessibility its vegetation 

 is perhaps better known than any other part lying far 

 within the Arctic circle. For this reason, and on account 

 of their high latitude, we have chosen the vegetation oi 

 the Spitzbergen Islands to illustrate the whole flora of 

 the Arctic regions. We have been influenced in this 

 choice too, by the fact that many of the species there 

 represented are indigenous in Britain. Most of these 

 species, it should be stated, are confined to the moun- 

 tains of the north of England and Scotland. ^ , ^, , 

 To give a general idea of the whole flora of the North 

 Frigid Zone,\e may quote a few of Dr. Hooker's figures. 

 By way of explanation it should be mentioned that Dr. 

 Hooker takes a very broad view of species, and many forms 

 considered as distinct species by some botanists here count 

 as varieties. The more recent additions to the flora ot 

 Spitzbergen would not materially alter these figures, be- 

 cause the same species were all, or nearly all, previously 

 known to exist in Arctic Continental Europe or America. 

 A few deductions would also probably have to be made. 

 For instance, the Reed-mace, ?)'///«, appears to have been 

 included by mistake in the list of Arctic American plants. 

 The total number of species of flowering plants— with 



which alone we shall concern ourselves— given, is 762, o 

 which about fifty are exclusively confined lo the Arctic 

 rc'dons. A very large proportion of these are found in 

 Scandinavia, south of the Arctic circle, and reappear in 

 the Alps ; a few reach the Alpine regions of the moun- 

 tains of India and Africa, and a few reappear in the 

 extreme south of the southern hemisphere. In a less 

 decree the same thing occurs from north to south on the 

 Ainerican continent. Of these 762 species, 616 have been 

 observed in Arctic Europe, 233 in Arctic Asia, 364 in 

 Arctic West America, 379 in Arctic East America, and 

 207 in Arctic Greenland. From the proportions the 

 respective figures for the five different areas bear to the 

 total, it will be seen that nearly all the areas must have a 

 majo'rity of species in common, and that each area has 

 very few species peculiar to itself. Before proceeding to 

 give a sketch of the flora of Spitzbergen, there is one 

 rem.arkable fact deserving of speci.al notice. Of the 

 207 species found in Greenland, 195 are Scandinavian 

 types, and only 12 are American or Asiatic types. 



A glance at the map for the position of the Spitzbergen 

 :-roup will enable the reader to realise more fully 

 Uie interest attached to the investigation of the plants 

 and animals of a small isolated tract of land in so 

 high a latitude— between 76° 33' and So° 50— espe- 

 cially when told that the highest point at which flowering 

 plants have hitherto been seen is about 82°, or within 8 

 of the pole, in Smith's Sound. The geological formation 

 of the group is of the earliest. So far as at present known 

 it consists of granite and other crystalline rocks, and in 

 the south traces of the Carboniferous and Permian strata 

 have been discovered. The climate of Spitzbergen is 

 modified to a certain extent, hke the whole of Western 

 Europe, by oceanic streams flowing from the hot regions 

 northwards. Nevertheless, it is exceedingly rigorous, as 

 may be imagined from the fact that the sun never rises 

 more than 37° above the horizon, and the winter is of ten 

 months' duration. From the observations of Phipps, 

 Parry, Scoresby, and several foreign explorers, the mean 

 temperature of July, the warmest month, has been esti- 

 mated at about 37° Fahr., and the highest point ob- 

 served by Scoresby was 51° on the 29th of July, 1815. 

 The mean temperature of the year is about 17 1 ahr., and 

 the mean temperature of the three winter months (Dec., 

 Jan and Feb.) is calculated at about zero of Fahrenheit. 

 Of course the preceding figures must be treated as very 

 rough approximations only. ,• , > 



From the foregoing brief sketch of the climatal 

 and other conditions of Spitzbergen, a very limited 

 number of flowering plants would be expected to 

 thrive, but at least one hundred species have been 

 observed— a comparatively rich flora, when we con- 

 sider that it is only in the most favourable situations that 

 they can exist at all. Nearly the whole of the vegetation 

 consists of herbaceous perennials, about one-third being 

 grasses, sedges, and rushes. The nearest approach to 

 woody vegetation are the crowberry l,Empetrummgrum\ 

 two species of willow {Salix reticulata and S polaris), 

 and Andromeda ictragona, an Ericaceous under-shrub, 

 neither of which rises more than a few inches above the 

 soil Taking the families in their natural sequence, we 

 have--i. Ranunculacea: : six species of Ranunculus, and 

 probably seven, a fragment in the Kew Herbarium, col- 

 lected by the Rev. Mr. Eaton, appearmg to be h. acns 

 2. Papaveracex : Papavcr nudicauk, a pretty dwarf 

 yellow flowered poppy. 3- Crucifers ; about eighteen 

 species, including Cardamine prate nsn; \,tn^?^oitsoi 

 Vraba, and one species of scurvy grass, Cochleariajuie- 

 ./;-,,/,^; perhaps the only esculent vegetable found m 

 Spitzbergen, which has proved most valuable to the crews 

 of the vessels that have touched there. 4. Caryophy lex . 

 about a dozen species, including the following Br tish- 



Silene acaulis, Arenaria "^i^'^^^ A'^f' ^lla^^A 

 A. rubella. 5. Rosaces : four species of Potenttlla and 



