26o 



NA rURE 



[Al'KIL 29, 1909 



for with special attention this year, as the sliower is sup- 

 posed to owe its parentage to Halley's comet. The latter 

 is approaching the sun rapidly, and will probably be dis- 

 covered next September. 



" Should the meteors prove to be unusually abundant 

 this year and in igio, the fact may be accepted as con- 

 <:lusive evidence that they are directly associated with 

 Halley's comet. Experience has proved that meteors may 

 swarm in front of a parent comet as well as behind it. 

 Prof. Newton pointed out that the Andromedid meteors 

 precede Biela's comet to a distance of 300 millions of miles 

 iilong the orbit. 



" At Greenwich the radiant of the Aquarids does not 

 rise until about 1.30 a.m., so that observations will be 

 useless before that time, and there is only a short interval 

 left for effective watching, for daylight has so far 

 advanced at 3 a.m. that only really conspicuous meteors 

 can be observed. This year the moon will be full, and 

 her strong light will obliterate the fainter meteors, but 

 the Aquarids are generally pretty bright, with long flights 

 of 40 or 50 degrees, so tliat should the shower abundantly 

 return this year it may be expected to present a striking 

 aspect, notwithstanding the presence of our satellite." 



Comet Morehouse, 1908c. — This comet was observed 

 by Prof. F. Ristenpart at Santiago de Chile on March 28 

 and 30, and the observations show that, on these dates, 

 the ephemeris published by Herr Ebell in No. 4296 of the 

 Astronoinischc Nachrichten required corrections of 

 -I- 2m. 2s., — i-o', and -l-im. 43s., —2-2', respectively (Astro- 

 nomische Nacliriclilen, No. 4318). 



The " Original " Canals of the Martian Doubles. — 

 Usually the twin lines forming the double canals on Mars 

 are equally intense, but on occasifcns one line appears to 

 'be more conspicuous than its fellow. The reduction of 

 Prof. Lowell's 1907 observations shows that, with one or 

 two exceptions, it is always the same canal of any pair 

 that becomes weakened, sometimes to extinction. 



A table given in Bulletin No. 37 of the Lowell Observa- 

 tory shows that, of twenty-two double canals observed 

 during the opposition of 1907, eighteen definitely presented 

 the phenomenon of unequal intensities. Of those, sixteen 

 always showed the one line of the pair, the " original " 

 ■canal as Prof. Lowell names it, stronger than the other ; 

 the period of observation covered the epoch of minimum 

 visibility of the doubles. 



The two exceptional canals were the Gihon and the 

 Is, and in both cases there is a possible explanation of 

 Their apparently anomalous behaviour. For the former this 

 depends upon the fact that when the eastern line was the 

 stronger the canal was still being fed from the north 

 polar cap, whilst when the western line preponderated the 

 canal was sharing in the general southern darkening of 

 the canals of the southern hemisphere. A similar explana- 

 tion holds in the case of Is. Comparisons with 

 Schiaparelli's observations confirm the phenomenon. 



Chromospheric Calcium Lines in Furnace Spectra. — 

 In No. 32 of Contributions from the Mount Wilson Solar 

 Observatory Dr. A. S. King discusses the behaviour of the 

 calcium lines H, K, and A 4227 in the spectrum obtained 

 by heating calcium to various temperatures, and under 

 varying conditions of density, in the electric furnace. 



His experiments at the Pasadena laboratory show that 

 whilst the line 4227 appears at a low temperature, and is 

 not sensitive to increases of temperature, it is enormously 

 strengthened by increasing the amount of calcium vapour 

 ■present. On the other hand, H and K do not appear until 

 the temperature approaches 2500° C, and are very sensi- 

 tive to temperature variation, whilst but little affected by 

 increasing the quantity of calcium vapour. 



Dr. King points out that although these results do not 

 throw much light on the study of sun-spot spectra, thev 

 are in strict accordance with eclipse observations of the 

 chromosphere. H and K appear alone in the higher 

 regions of prominences, but 4227 does not appear until 

 the chromospheric vapours reach a considerable density. 



Mount Wilson Solar Observatory Report. — Prof. 

 Hale's report of the work done at the Mount Wilson 

 Observatory during iqnS is too compendious to notice in 

 ■detail, and many of the results mentioned have already 



NO. 2061, VOL. So] 



been abstracted in these columns, but there are one or two 

 points which may be mentioned. Prof. Hale states that 

 the electric-furnace experiments have confirmed the con- 

 clusion that the temperature of the vapours of Fe, Ti 

 &c., in sun-spots is lower than that in the " reversing 

 layer " outside spots. 



Mr. Abbot, of the Smithsonian Institution, is still 

 engaged in the studies of the solar constant, and arrange- 

 ments have been made by the institution to construct a 

 permanent station on Mount Wilson, where such studies 

 will be regularly maintained. The total number of spectro- 

 heliograms taken with the s-feet spectroheliograph 

 amounted to 5196 on September 30, 1908. 



An investigation dealing with the absorption and scatter- 

 ing of light in the solar atmosphere has just been com- 

 pleted by Prof. E. F. Nichols, of Columbia University, and 

 the observations are in course of reduction. 



A spectrocomparator has been added to the laboratory 

 equipment, and is being used for the comparison of the 

 intensities of spectrum lines. The definite reduction of the 

 photographic sun-spot spectra is being carried out, and 

 some idea of the magnitude of the task is afforded by the 

 statement that between \ 5000 and \ 5500 there are more 

 than 1500 lines for which wave-lengths and laboratory 

 identifications have to be determined. 



THE ELECTRIFICATION OF RAILWAYS. 

 HTHE presidential address delivered by Mr. John A. F. 

 Asplnall in the lecture hall of the Institution of 

 Mechanical Engineers on Friday, April 23, proved to be a 

 most agreeable surprise to those members who were 

 fortunate enough to be present. Addresses on such 

 occasions are apt to take a historical or academical form, 

 and many experiences of this character served to emphasise 

 the interest taken by the audience in Mr. Asplnall 's clear 

 account of the electrification and experiences gained in the 

 working of the Liverpool and Southport branch of the 

 Lancashire and Yorkshire Railway, of which the author 

 Is the distinguished head, since its inception in October, 

 1902. 



It is too often stated that a general electrification of 

 our railways would be of very great advantage. In certain 

 instances this worli can be undertaken with great com- 

 mercial success, but each case has to be considered with 

 great care, not only on account of the costly character 

 of the work, but also because the conditions upon which 

 success or failure depend vary in almost every place or 

 district. To warrant the electric equipment of a main 

 line of railway, dealing in present circumstances with long 

 steam-hauled trains at high speed for long distances with- 

 out a stop, some great commercial advantage must be 

 shown. Business men can easily arrange their journeys 

 at present between Liverpool or Manchester and London 

 so as to have five hours in town. Even supposing a speed 

 of 120 miles per hour to be attained by electric traction, 

 the gain to the traveller would be small, while the in- 

 creased cost to the railway would be enormous. Again, 

 such fast trains would practically prohibit the use of the 

 same tracks for the running of slower local trains, and 

 would necessitate separate traclis for these. The earning 

 capacity of the express tracks would thus be diminished. 



On the other hand, in the case of many suburban lines 

 from our great cities, electrification will at once double 

 the train-carrying capacity of the tracks, while in others 

 it will allow a greater time space between trains, which 

 may be utilised for the passage of steam-worked express 

 trains coming In from the more distant parts of the line. 

 In a district where a railway has had its tracks paralleled 

 by tramways, the creation of an electric railway service 

 will have the immediate effect of bringing back large 

 numbers of passengers who have used tlie trams in the 

 early stages of their construction, but who find that they 

 cannot tolerate the great waste of time which results from 

 the very slow speed and the many stops due to the crowded 

 streets through which the trams have to run. Some of 

 the advantages of electrification for local services are : — 



fa) High schedule journey speed. 



(b) Much more frequent service when required. 



(c) Increased acceleration and deceleration. 



