110 British Association, 



Sir William Betham then added a short notice of a Hindoo Legend 

 from a paper in the Asiatic Researches, by Captain Wilford, showing 

 that the Cabiric mysteries existed in India, under the names Cubear 

 or Cuvera, Asyoruca, Asyotcerso, Cashmala and Carmala ; and that 

 these deities or genii superintended mining and metals. 



Professor Mac Cullagh read a paper *' On the Chronology of 



Egypt." 



BRJTISH ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE : 

 MEETING OF 1837, AT LIVERPOOL. 



Section of Mathematical and Physical Science, Sept. 12. 



Dr. Robinson, of Armagh, read a Report of the Determination of 

 the Constant of Lunar Nutation from a discussion of the Greenwich 

 Observations. 



The author commenced by giving a sketch of the commencement of 

 accurate astronomy, under the auspices of Bradley, by his brilliant 

 discoveries of the aberration of light and the nutation of the earth's 

 axis, demonstrating, that a degree of precision, until then deemed 

 unattainable in astronomical observations, was perfectly possible. 

 The impulse then given has not since ceased to effect the movements 

 of astronomical discovery. Yet from this day, it must be acknow- 

 ledged, that, in regard to both aberration and nutation, nothing was 

 added to the researches of Bradley, until within a few years, when 

 Struve, Brinkley, and Richardson resumed the inquiry. He then 

 sketched the progress of each of these, and stated, that the constant 

 of nutation deduced by Brinkley was that generally adopted by Bri- 

 tish astronomers. In Germany, however, the authority of Bessel had 

 introduced and given currency to a different value for this important 

 element of calculation, deduced from the calculations of Von Lin- 

 denau; and although the two values differ only one-fourth of a se- 

 cond, which is less than the millionth part of the length of the tele- 

 scopes generally used in observing, yet such is the accuracy required 

 in the modern researches of astronomy, that even this evanescent 

 quantity of error is considered as a disgrace. This stigma, he trusted, 

 was now removed by the work which the aid of the British Association 

 had enabled him to perform, and of which he now intended to give a 

 brief notice. 



Dr. Robinson then referred to the labour of reducing observations, 

 as actually taken, in consequence of the refraction of light, tlie aber- 

 ration of the stars caused by the progressive propagation of light, the 

 proper motions of the stars, and the united effect of all the movements 

 impressed with the earth upon the actual place of the observer. Of 

 these, the impressions upon the axis of the earth are pre-eminent, and 

 the largest of them in amount has been long known under the name 

 of the Precession of the Equinoxes — this is well known both as to its 

 laws and amount ; the remaining three are termed Nutations, of 

 which one completes its course in a fortnight, and is never so large as 

 one-tenth of a second — the theory of this is sufficiently known j a 

 second completes its cycle in half a year, and when greatest may 



