NOTES. 



ASTRONOMY. 



By A. C. D. Crommelin, B.A., D.Sc, F.R.A.S. 



PHOTOGRAPHY OF THE MILKY WAY. — Mr. 

 d'Esterre's results should be an encouragement to the 

 possessors of small photographic apparatus. He has selected 

 a limited region of the Milky Way, near the great Perseus 

 cluster, and keeps a constant photographic patrol upon it with 

 a six and a half-inch Voigtlander camera and some smaller 

 instruments, also occasional visual observation with a fifteen- 

 inch reflector. His zeal has been rewarded by the discovery 

 of a faint Nova (87, 1911), which is interesting as being one 

 component of a double star ; also several variables. Observa- 

 tions of these are contained in Astronomische Nachrichten, 

 No. 4623, with diagrams of the fields. 



It is likely that observers who selected other regions, and 

 followed them with the same pertinacity, would reap similar 

 harvests. 



ATTRACTION OF SUNSPOTS FOR PRO- 

 MINENCES. — The Astrophysical Journal for November 

 contains an interesting article by Mr. F. Slocum on the large 

 sunspot of October, 1910, illustrated by several spectro- 

 heliograms in calcium light. The prominences round the 

 spot appear to have been strongly attracted by it, and were 

 seen in successive photographs to approach it with accelerated 

 motion. Professor Hale and Mr. Evershed had previously 

 noticed that the gases round sunspots were moving inwards, 

 but their observations indicated that the inward motion was 

 retarded, not accelerated. It was formerly debated whether 

 sunspots were formed by inrushes or outrushes of gas. The 

 new observations would seem to favour the former, but it must 

 be remembered that an inrush at one level may be accom- 

 panied by an outrush at another. I remember being in a boat 

 on the Thames immediately over the outrush of water from a 

 lock-sluice; contrary to expectation a counter current carried 

 our boat violently against the lock gate. Any violent current 

 generally produces a backwash. In fact, Mr. Slocum finds 

 evidence of such outward motion on a few of the plates, but 

 it is less marked and less persistent than the inward motion. 



NOVA GEMINORUM (2).— The same number of The 

 Astrophysical Journal contains an interesting article by 

 Walter S. Adams and Arnold Kohlschutter on the spectrum of 

 this Nova. Photographic spectra on dates ranging from 1912, 

 March 22nd to August 19th, are reproduced, and the spectrum 

 of a Wolf-Rayet star is given for comparison with the last. 

 It has some points of resemblance, but great difference in 

 relative intensities of lines. The authors sum up the changes 

 in the Nova's spectrum thus: — 



(1) The continuous spectrum got steadily weaker. 



(2) An increase in the number and intensity of the nebular 



lines. The chief nebular line, X 5007, was first seen 

 on April 6th, and afterwards became very strong. 

 The second line, X 4959, was first seen on April 22nd, 

 and rapidly grew stronger. The nebular lines at 

 X 4364, 4687 also got strong in the later photographs. 



Using the narrowest and best-defined lines to find the 

 radial velocity of the Nova, they deduce a recession from the 

 Sun of ten kilometres per second, close to the mean of the 

 values nine kilometres, twelve kilometres, and seven kilo- 

 metres found by Curtiss, Plaskett, and Kiistner. They do 

 not consider that variation in the velocity is established, 

 though it is not impossible. 



They find no evidence of the presence of radium in the 

 Nova, which other observers had suspected. 



SIGNS OF REVIVING SOLAR ACTIVITY.— It is well- 

 known that the last sunspot cycle was abnormal : the maximum 



was delayed three or four years after the time deduced from 

 the eleven year period. There was also a double maximum. 

 It is therefore difficult to predict for the coming cycle, but we 

 may anticipate a revival in the near future. One sign of the 

 beginning of a new cycle is the outbreak of spots in higher 

 solar latitudes. Mr. Maunder noted at the December Meeting 

 of the British Astronomical Association that a spot had 

 appeared in relatively high latitude, which might be the 

 harbinger of the new cycle. Professor Schuster expects a 

 distinct awakening of activity about next May. This is based 

 on his four-year cycle of activity, whose reality is questioned 

 by some students of the Sun. In any case we are probably 

 near the beginning of the new cycle, and a careful watch 

 should be kept on the Sun. 



SOLAR ECLIPSES. — Our sympathies must be extended 

 to the numerous astronomers who visited Brazil last October 

 for the solar eclipse. Heavy rain prevented any results. An 

 interesting account of the English expedition is given by 

 Mr. Eddington in the January number of The Observatory. 

 The eclipse was an unusually dark one, and the descent of the 

 darkness and return of the light were both sudden. 



There will be an important total eclipse in August, 1914, 

 the central line crossing Norway, Sweden and Russia. The 

 official British expedition proposes to go to the Crimea, but 

 there are so many accessible points on the line that the 

 parties are likely to be widely distributed. The British 

 Astronomical Association will probably organise an expedition 

 to Norway. If it prove as great a social success as that of 

 1896, and is favoured by kindlier skies, no one is likely to 

 regret taking part in it. 



BOTANY 



By Professor F. Cavers, D.Sc, F.L.S. 



.BIOLOGY OF DESERT PLANTS.— Dr. D. T. Macdougal, 

 Director of the botanical research department in the Carnegie 

 Institution at Washington, has recently published (Ann. Bot., 

 Vol. XXVI) a further memoir on the " water-balance " of 

 desert plants. The water-conducting tissues of flowering 

 plants are closely connected with distensible tracts of tissue 

 (e.g., cortex and pith) which have an appreciable capacity for 

 the retention of water in plants of even the most sparing habit 

 and structure. As the ascending water-current passes from 

 the root-hairs to the leaves, some of it may go into such 

 masses of tissue forming reservoirs in the roots, stems, or 

 leaves ; this accumulated supply may be drawn out to the 

 transpiring cells when the pressure of the solution in the cell- 

 sap is overcome. All plants with massive stems may thus 

 carry a large balance of water, and this stored solution may 

 play an important part in the plant's life. The relatively 

 largest balances are borne by some of the species characteristic 

 of the arid regions of the south-western and southern parts of 

 North America, some parts of South America, and the southern 

 parts of Africa ; while North Africa, Asia, Australia, and arid 

 regions in high latitudes everywhere have but few plants with 

 a large water-balance. The present paper deals with observa- 

 tions made in the Tucson region of Arizona, which has a 

 winter rainy season and a wet midsummer, with a hot dry 

 fore-summer and arid after-summer. The total average annual 

 rainfall is about twelve inches only ; the extremest arid effects 

 are seen in June and July, when the humidity falls as low as 

 six per cent, with midday temperatures of 110° F. 



In desert regions the vegetation includes a number of 

 rapidly-maturing forms, which carry out their entire life 

 cycle during regular or irregular periods of rainfall, and 

 which are physiologically mesophytes — plants without any 

 marked adaptations for checking transpiration ; other forms 



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