]()1. 



KNOWLEDGE 



[May, 1902. 



Kliiiiuliijwra, oiii' of tlic tribiitarv cliiffs of Orissa At 

 tlif early age of ten, liaviug bei'ii taiiglit a little astrology 

 l)y ime of his uucles, lie bceamo most anxious to measure 

 on liis own account the jiosilious of the stars in their 

 nightly uiovemeuts, ami by the time that lie was fifteen 

 years of age and had learned to ealmilate the ephemerides 

 of the planets and of the risings and settings of stars, he 

 was deeply disapjioiuted to find liow great was the 

 discordance between his calculations and wiial he actually 

 obsen-ed. It was no wonder that he found discordances ; 

 uo two of the current Hindu almanacs agree in their 

 predictions, and one of the most widely circulated of the 

 Bengali almanacs may be as much as 4° out in the 

 longitude of a planet. 



In this difficulty Chandrasekhara had to work out his 

 problem unaided. He had to make his iustrumeuts for 

 himself, to some extent he had to devise them. The one 

 of wliich he was fondest is a tangent staff consisting of a 

 thin rod of wood twenty-four digits long, at the eud of 

 which is fixed another rod at right angles in the form of T. 

 The cross i>iece is notched and also pierced with hol.s 

 equal to the tangents of the angles formed at the free 

 extremity of the other rod. 



I'or many years he has been carefidly revising the 

 Siddhantas in order to bring them into conformity with 

 his observations made at the present period, and he has 

 been able to obtain a most astonishing degree of accuracy 

 in his results. Thus, the sidereal period for Mercury is 

 only 00007 days different from that adopted by Eurojieau 

 astronomers ; for Venus it is only 0'0028 days. The 

 mean inclinations of the orbits of the planets to the 

 ecliptic are correct to about a minute of arc. The errors 

 of the ephemerides com]>uted from liis uew^ constants are 

 reduced to about t>ne-tenth of those in some of the most 

 widely circulated Hindu almanacs. In his discussion of 

 the moon's motion, he made the discovery — independent 

 and original on his part — of the lunar evection, variation 

 and annual equation, which found no place in the earlier 

 Siddhantas. In much of his work he had the advantage 

 of compai'ing his observations with those of Bhaskara, 

 made more than seven hundred years earlier ; not indeed 

 that the latter had recorded his actual observations, but 

 it was possible to ascertain what they must have been from 

 the planetary elements which he had deduced from them. 

 Nevertheless, to have obtained such imjiortant results and 

 so high a degree of accuracy, by uaked-eye observations 

 and with entirely home-made instruments, and in the 

 utter absence of modern book learning, is a striking 

 illustration of what resolution can effect. 



Cliandrasekhara has been compared to Tycho Brahe, and 

 the comparison is in many ways a just one, though the 

 recluse of Orissa lacked many of the advantages possessed 

 by the noble Dane. As to the accuracy of Tycho's work, 

 it will be remembered that Kepler was led to the first of 

 his thi-ee great laws by finding that his theory of the 

 circular motion of the [ilanets was irreconcileable with an 

 observation of Mars by Tycho by eight minutes of arc — 

 but one-fourth of the moon's diameter— Kepler concluding 

 that it was impossible tliat so good an observer could be 

 in error to this extent, abandoned his hypothesis and tried 

 that of motion in an ellipse. 



In the recluse of the Orissa village, we seem to see 

 reincarnated, as it were, one of the early fathers of the 

 science, long centuries ere the telescope was dreamed of, as 

 he grappled with the problems which the jjlanetary move- 

 ments offered to him for solution. More than that, he 

 affords an example of the achievements within the reach 

 of the naked-eye astronomers, and a telling illustration of 

 the i>recision which patience and jiractice can give to hand 



and eye. And these are always needed. For be the 

 telescope ever so good and powerful, still that which is by 

 far the most important is the man at the eye-end. 



CLOUDS. 



By Commander 1>. Wilson Bakker, k.n.k., k.k.s.e, 



F.R. MET.SOC. etc. 



Those who are professionally engaged in the scientific 

 work of weather bureaux recognise the im]>ortauce of 

 accurate observations of cloud forms and nature, and 

 much good work has been done in this connection in 

 recent years by scientific observers in England, Australia, 

 and the United States ; but, as a popular study, Nephology 

 IS almost entirely overlooked, and this notwithstanding 

 the fact that, perhaps, no branch of knowledge offers 

 greater facility and ease of acquisition. Each cloud has 

 its history fraught with meaning; its open secret is writ 

 on its face, and may be read by anyone who will give 

 himself a little trouble, nor need he go deeply into the 

 study in order to make observations interesting to himself, 

 and perhaps of great use in the furthering and perfecting 

 of weather lore. To the ancients, the sky was doubtless an 

 object of constant remark and interest, and possibly their 

 intuitive knowledge of weather forecasting was much more 

 accurate than ours. The dwellers in our modern cities see 

 little of the sky, clouds have no interest for them beyond 

 the personal consideration as to the advisability of taking 

 out an umbrella or not. But farmers, fishermen, sailors 

 and others following open-air avocations arc dependent on 

 the weather, and to be wise in its forecast is of importance 

 to them. To these, especially, cloud study should appeal ; 

 it cannot fail to be profitable to them in their personal 

 work, and they have all the opportunity, if the will be 

 there, to forward the general knowledge of the subject by 

 careful ])ainstaking oliservations, which they may transmit 

 to those scieutificallv engaged in dealing with weather 



Fig. l.-SU 



laws, and thus assist in the elucidation of questions on 

 which we are at present but very imperfectly informed. 



In this article the broad distinctions of clouds will be 

 dealt with. There are two well-defined types — Stratus 



