Januaby 2, 1899.] 



KNOWLEDGE. 



17 



An irrefular line on the horizon to the north marks 

 the place where the far distant range of the NOgherries 

 lies, the rivals of the Pulney Hills. It was a question 

 for a time of erecting the new elevated Indian observatory 

 on the Nilgherry range, but the annual records of the 

 necessary climatic conditions carefully observed in both 

 places turned the balance in favour of the latter, for which 

 the following data, as published by Mr. Michie-Smith in 

 the Publications of the Arts Societij of the Pacific, were 

 reported in a local paper in June, 1895. 



The mean daily temperature varied in one year from 

 5J;-2" F. in December to 62-2" F. in May, the mean for 

 the year being 58'5' F. The mean humidity varied from 

 forty-seven per cent, in March to eightythi-ee per cent, in 

 August, the mean for the year being seventy-two per 

 cent. The actual number of days on which 'Ol inch and 

 upwards- of rain fell was one hundred and fifty-five, dis- 

 tributed through the twelve months thus : — 



4, 5, 3, 16, 19, 19, 21, 21, 8, 21, 7, 8. 

 The total rainfall was 47'58 inches, but the average over 

 a number of years, for a station a mile and a half distant, 

 and nearer the edge of the cUff, was sixty-one inches. 

 There were two thousand and fifty-sis hours of bright 

 sunshine throughout the year, and " my own experience, ' 

 said Mr. Michie-Smith, " during a number of short visits, 

 is that a night which remains cloudy throughout is 

 very rare, and that a large proportion of the nights are 

 brilliantly clear." 



The building is erected on the rock, and has the form 

 of an irregular cross, the main branch of which is shorter 

 than the arms, and lies due east and west over a total length 

 of seventy-two feet outside. The two arms are stretched 

 north and south, symmetrically covering together a total 

 length of eighty-eight feet. Each of them is terminated 

 by a tower sixteen feet inside diameter and nineteen feet 

 high, of which seven only remain to be completed. The 

 upper floor of the observation room will be reached in 

 each by an easy winding staircase, in small hexagonal 

 towexs, protruding symmetrically on the eastern side. 

 The two arms will be completed first, and the towers will 

 in March next be ready to receive their hemispherical 

 domes, covered in papier-mache, the iron frames of which 

 will not find their way up to the observatory without 

 some trouble, as nothing is carried from the plain but by 

 coolies or ponies. The remainder of the building has 

 just now risen two or three feet above the foundation, 

 but further directions must be waited for before the work 

 can be continued. Whatever be altered, one thing now 

 partly begim will remain, the spectroscopic room at the 

 west end or head of the cross. The rays, either solar or 

 stellar, it will admit for investigation, will be reflected by a 

 clockwork polar heliostat, at the top of a long earthenware 

 tube, of one inch to two inch bore, placed due north and 

 south, on iron brackets, along the front part of the north 

 tower. They will be analysed by a Kowland grating 

 spectroscope, constructed by the late A. Hilger. The 

 instrument is actually at Madras. Although the present 

 intention is to study solar physics only, it is very probable 

 that the astronomer in charge of such a favourably situated 

 observatory will not be satisfied with this, but wiU also 

 study stellar physics. Eye-witnesses alone can realize 

 what nights are on tropical hills at this height, and my 

 personal experience of three months spent on these hills 

 ten years ago would induce me to speak in enthusiastic 

 terms. Not once alone did I see Jupiter shining in such 

 a manner, from near the zenith, that it cast on white 

 paper a well-defined shadow of a hair, and its light 

 passing through the foliage of the trees showed on the 

 ground a shadow as neatly defined as if produced by 



an electric arc without diffusing globe. And yesterday 

 evening, Yenus, which attained on the 21st instant, its 

 maximum of brilliancy after the " conjunction," cast, in 

 spite of a brilliant six day old crescent moon, on a white 

 wall a definite dark shadow of pillars supporting a 

 verandah. The number of stars visible to the naked eye 

 when the moon does not light up the atmosphere can be 

 conceived only by those who have seen it for themselves. 

 The first report of the Kodaikanal Observatory will con- 

 tain interesting details on this subject, and stand advan- 

 tageously in comparison with reports from other high-level 

 observatories. Let us hope that when communication with 

 Kodaikanal is cheaper owing to the railway line to be opened 

 in January next from Ammayanayakanoor to the Tope, 

 and a cable elevator worked by electric power which a 

 Madras firm proposes to stretch over the Pambar falls and 

 valley up to Kodaikanal, the trustees of the Observatory 

 will be bolder to extend their work, and leave no advan- 

 tage of so favourable and exceptional a position unused. 

 R. DE Beaueepaire Lauvagxy, s.j. 

 Astronomer of the Zi-ka-Wei Observatory. 

 Kodaikanal, India, 



21st October, 1898. 



[May I take the opportunity of Father Lauvagny's 

 account of the important enterprise now progressing under 

 Prof. Michie-Smith's able direction, to correct an error 

 which crept into my description of the instrument em- 

 ployed by the latter during the late solar eclipse at Salidol, 

 India? (Knowledge, July, 1898, p. 156.) Prof. Michie- 

 Smith's telescope was not pointed to the Sun, but to the 

 Pole, being placed parallel to the Earth's axis, and fed by 

 a heliostat. — E. 'Walter Mauxdek.] 



VARIABLE STARS. 

 To the Editors of Knowledge. 



Sirs, — Among variable stars of long period there are few 

 that stand more conspicuous for changes in colour and 

 fluctuations of light than S. Virginis and R. Hydrse. And 

 the interest in them is increased from the fact that they 

 remain, in this latitude at least, a long time in view and 

 within the power of small optical instruments. These 

 stars have grown in interest in the last three or four years, 

 and for these reasons, and also from the fact that R. Hydras 

 does not remain long above your horizon, I submit the 

 following ephemerides : — 



