December 8, 19 lo] 



NATURE 



181 



small increase of probable error, say 40 per cent., appear- 

 ing when the dispersion is divided by three. 



In the early-type stars the diffuseness of the available 

 lines in the spectrum increases the probable error very 

 rapidly, and Mr. Plaskett is convinced that physical causes 

 in the star's atmosphere are contributory to this increase. 



For solar-type stars it would appear that the average 

 probable error of a good three-prism determination need 

 not exceed ' ±0-5 km. per sec, while with one prism 

 ±0-70 km. might be expected in good work. If stars of 

 in earlier-t}pe spectrum are dealt with, ±2 to ±11 km. 

 i)er sec. is a moderate estimate of the probable error. 

 Finally, Mr. Plaskett suggests that with solar . stars the 

 i^reater part of the error accrues from instrumental causes, 

 the errors of measurement only accounting for about one- 

 third or less. 



The Photogr.aphic Magnitudes of Stars. — In Circular 

 No. 160 of the Harvard College Observatory Prof. E. C. 

 Pickering discusses the progress made, to July, in the 

 -tablishment of a method for determining photographic 

 nagnitudes and of a scale for recording them. 



Three methods have been found to give satisfactory 

 results. The first depends upon the law that stars of the 

 ~ame spectral class have the same colour and has been 

 sted with concordant results ; the following values are 

 interesting as giving the constants necessary to reduce 

 photometric to photographic magnitudes according to 

 spectral class : — 



B A F G K M 



-0*31 000 +0-32 +071 +1-17 +1-68 



Thus if the visual magnitude of a star is 500 and the 

 spectrum is of type B, the photographic magnitude is 

 4-69, but if the spectrum is of the G type the photographic 

 magnitude is 5-71. 



The second method, in which a standard " polar 

 --quence " of stars is photographed on the same plate 

 and under similar conditions as the stars to be measured, 

 has been already described in these columns, but it is 

 interesting to note that the work has been extended to 

 stars so faint as the twentieth magnitude, and it is hoped, 

 ere long, to publish definitive magnitudes for a great 

 number of stars in both hemispheres. About 11,000 

 measures of 200 photographs have already been made ; for 

 stars fainter than magnitude 14, for which long exposures 

 are necessary, it has been found that this method is not 

 so suitable. For such stars it has been found that the 

 third method, in which a small circular prism of very 

 small angle is attached to the centre of the objective, is 

 better ; the small prism diverts a known proportion of the 

 light from each image into a secondary image, and so 

 provides a ratio scale. Prof. Pickering discusses the 

 difficulties presented by the problem, and states that 

 although the results already attained are very hopeful, 

 uich remains yet to be done. 



The same problem is also attacked by Herr E. Hertz- 

 jrung in No. 4452 of the Astronomische Nachrichten, 



ho proposes a tried method in which the density of a 

 direct image is compared with an image, on the same 

 plate, produced when a grating is placed before the 

 objective. 



Proper Motion of the Star B. 0.4-33° 99- — Whilst 

 making observations of the minor planet 19 10 KU, Dr. 

 Abetti was led to suspect that one of his comparison stars, 

 ^■D-+33° 99 (.AG. Lei. 226), has a large proper motion. 

 Subsequent investigation and calculations show that this 

 proper motion amounts to —0027 + 00045. and — o-34± 



•oo". The magnitude of this star is 8-5 (Astronomische 



^ achrichten. No. 4453). 



o 



THE NEW METEOROLOGICAL OFFICE. 

 N Thursday, December i, a large party assembled at 

 - the new Meteorological Office at 'the corner of 

 'xhibition Road and Imperial Institute Road on the invita- 

 jn of the Meteorological Committee. 



The committee was originally appointed by H.M. 



■ reasury in 1905 to control the administration of the 



Parliamentary grant for meteorology. Its inexpressive 



title gives little indication of its responsibility to the 



NO. 2145, VOL. 85] 



country and, indirectly, to the world at large. It consists 

 of the director of the office, Dr. W. N. Shaw, who is 

 ex officio chairman ; the hydrographer of the Navv, Rear- 

 .Admiral H. E. Purey Cust ; Mr. G. L. Barstow', of the 

 Treasury; Captain J. M. Harvey, of the Board of Trade; 

 Mr. T. H. Middleton, of the Board of Agriculture and 

 Fisheries; with Sir G. H. Darwin, F.R.S., and Prof. 

 Arthur Schuster, F.R.S., the nominees of the Royal 

 Society. 



The work of the office goes back, in continuity, to the 

 original establishment of a Meteorological Department of 

 the Board of Trade for the joint service of the Navy and 

 the mercantile marine under the superintendence of 

 Admiral FitzRoy, the naval officer who, as captain of the 

 Beagle, had carried Charles Darwin round the world. 

 The motive power for the establishment of a special depart- 

 ment for meteorology came from a maritime conference 

 held in Brussels in 1853, in which Lieut. Maury, of the 

 Lnited States Navy, a well-known geographer and meteor- 

 ologist, took a leading part. The primary object of the 

 office was the collection and discussion on an organised 

 plan of meteorological observations made at sea ; but when 

 Leverrier began collecting daily observations by telegraph 

 in France, FitzRoy associated himself wnth the idea', and 

 in i860 he introduced a system of weather telegraphy with 

 storm warnings and forecasts which in 1861 were pub- 

 lished in the newspaf>ers. 



• This line of action evoked a great deal of criticism on 

 the part of scientific authorities, and it is doubtful whether 

 meteorology, at that time a bashful debuiante among the 

 sciences, has ever been forgiven for so shocking a faux 

 pas. It is true that the system of warnings was continued 

 after FitzRoy 's death at the instance of the Board of 

 Trade, influenced by several memorials to Parliament, and 

 that in 1879, after the issue of forecasts had been dutifuUv 

 suppressed for twelve years, in a report of the council 

 then in control of the office, appointed bv the Roval Society 

 and made up of the great names of Henry J.'S, Smith, 

 Warren De la Rue, Frederic J. O. Evans, Francis Galton, 

 George Gabriel Stokes, and Richard Strachey, the foUow^- 

 ing paragraph appears : — " For several years" forecasts not 

 intended for publication had been daily prepared in the 

 office, and the experience thus gained' by the staff has 

 emboldened the council to announce their readiness to com- 

 mence in April, 1879, the issue to the public of forecasts 

 for the different parts of the United Kingdom," and that 

 the issue has been continued ever since; but the natural 

 hesitation which men of science fee! about publishing their 

 conclusions before they have had an opportunity of verify- 

 ing them has always overshadowed that side of the office 

 work. To that circumstance, combined with the frigidity 

 with which the young science has been treated bv her elder 

 sisters, it is probably due that, while prolonged effort has 

 been devoted to the preparation of forecasts twice, or even 

 three times a day, for a whole generation, and while the 

 rule that no forecast shall be formulated without first 

 setting out the data and the grounds for the inference has 

 been rigorously enforced, yet the issue of the forecasts has 

 been left practically to the newspapers. It seems other- 

 wise inexplicable that no general system of distribution of 

 forecasts by telegraph should have been adopted in this 

 country. 



FitzRoy died in 1865, and the office became the subject 

 of inquiry by a Government committee, with the result 

 that in 1867 the control of the Parliamentary grant was 

 handed over to a committee of the Royal Societv-, with 

 Sir E. Sabine, the president of the Royal Society, as 

 chairman. At the same time provision was made for 

 marine meteorology and w^eather telegraphy to be 

 associated with the work of fully equipped meteorological 

 observatories of the first order, six of which were forth- 

 with established, namely, Falmouth, Stonvhurst, .Aber- 

 deen, Glasgow, Armagh, and Valencia, in addition to Kew, 

 which had become the central observatory of the system. 



Continuity between FitzRoy 's depa'rtment and the 

 Meteorological Office was maintained bv the transfer of 

 all the duties of the department and a number of members 

 of the staff to the new committee. Mr. T. H. Babington, 

 however, who took over the management of the department 

 on FitzRoy's death, was not transferred; Mr. R. H Scott 

 was appointed director of the new establishment with- 



