54 



ASTEONOMICAL PHENOMENA AND PEOGEESS. 



to account for their strong blue color on that 

 hypothesis. Yet the same difficulty would be 

 experienced in the case of Mars, whose poles 

 appear light blue, or light green, to many ob- 

 servers ; and the existence of ice on those 

 poles may be considered as proved. The uni- 

 formity of the red belts would seem to indicate 

 that the whole of the surface over which they 

 extend must possess the same character. Mr. 

 Browning concludes that, if the color is due to 

 the soil, the seas must be confined to the poles 

 of the planet. 



The Color of the Moon and Stars. Different 

 observers had made different reports upon the 

 amount of color visible in the moon during the 

 same lunar eclipse. These discrepancies sug- 

 gested to Mr. John Browning an inquiry into 

 the causes of them. In his own observations 

 of a lunar eclipse in which coppery or blue tints 

 had been generally seen, he had failed to de- 

 tect either of those colors. The explanation 

 he found to be this : that he had used a tele- 

 scope of larger diameter than the telescopes em- 

 ployed by most observers. The observers who 

 had instruments of only three or four inches 

 aperture spoke of the color as being less than 

 usual, but very noticeable; those who had 

 telescopes of seven or eight inches aperture 

 saw very little color ; and observers with tele- 

 scopes of 10J inches aperture, or a 12^-inch. sil- 

 vered glass speculum, could not detect any 

 color at all. Mr. Browning thus concludes a 

 paper upon the subject, presented by him to 

 the Eoyal Astronomical Society : 



It is true that I failed equally in detecting color 

 with a four-inch object-glass, but I account for this by 

 supposing that the sensitiveness of my eye to faint- 

 colored light had been injured by the glare^of the 

 moon in the large aperture. Experimenting in con- 

 nection with this subject, I have noticed that the choc- 

 olate color of the so-called belts of Jupiter is much 

 more perceptible with 6 inches aperture than with 12 

 inqhes. Again, a small star in the cluster in Perseus 

 appears of an indigo-blue with 81- inches, Prussian- 

 blue with 10i inches, and royal-blue with 12? inches of 

 aperture. It follows from this that colors estimated 

 by comparison with the ingenious chromatic scale of 

 Admiral Smyth, in which each color is represented of 

 four different degrees of intensity, will not possess any- 

 relative value unless taken in connection with the 

 aperture employed when the color was estimated. 

 Were due allowance made for this disturbing influence 

 of variation of aperture, I think many discrepancies 

 "between the colors attributed to double stars oy dif- 

 ferent observers might probably be reconciled. 



On the Fall of Bain as affected by the Moon. 

 Mr. Pliny Earl Chase has contributed to the 

 proceedings of the American Philosophical So- 

 ciety a paper on this subj ect. His attention was 

 specially called to it by an article by Mr. George 

 Dines in the Proceedings of the Meteorological 

 Society No. 36, which presented a summary of 

 observations of rain which fell during each day 

 of the moon's age, through a period, with few 

 interruptions, of over forty years. Upon those 

 data the author based the "decided opinion 

 that the fall of rain is in no way influenced by 

 the changes of the moon or the moon's age." Mr. 

 Chase, however, upon a careful examination of 



the same tables, deduces the conclusion that, 

 notwithstanding the complete veiling of all the 

 disturbances which 'may be due to the moon's 

 variable distance and decimation, there was a 

 marked tendency to increase at quadrature and 

 to decrease at syzygy, both in the amount of 

 rain and in the number of rainy days. This 

 tendency, which becomes evident even in the 

 majority of the" five years 1 groupings, is uni- 

 formly shown in all the groups of ten years, 

 twenty years, and forty years, as well as in the 

 number of rainy days and in the number of 

 heavy rains during the entire period. 



Mr. Chase gives the following forty years' 

 aggregates (1825 to 1864 inclusive) at Surrey, 

 the place of observations referred to by Mr. 

 Dines, and at the Pennsylvania Hospital, Phil- 

 adelphia : 



Surrey. Philadelphia. 



"Week of new moon 98.2 97.6 



" first quarter 103.1 100.3 



" full moon 97.4 95.8 



" last quarter 101.4 106.3 



Mr. J. H. N. Hennessey, First Assistant on 

 the great Trigonometrical Survey of India, in a 

 paper to the Eoyal Society, alludes to a record 

 of the rainfall at Mussoorie extending over thir- 

 teen years, and remarks : 



The results tabulated have been obtained by 

 employing an average daily fall as the means 

 for comparing the fall at " the changes " with 

 that at intermediate intervals. The annual 

 average result may be stated thus : 



Inch. 



At " the changes" of the moon the mean daily 

 fall of rain is 0.466 



Between " the changes " of the moon the mean 

 daily fall is 0.525 



which is in opposition to the popular belief on 

 the subject. 



The Melbourne Telescope. This great instru- 

 ment, manufactured by Mr. Grubb, of Dublin, 

 has been examined and favorably reported on 

 by a committee of the Eoyal Society, composed 

 of Earl Eosse, Dr. Eobinson, and Mr. Warren 

 De la Eue. The telescope is of the reflecting 

 order. The reflector is of metal a fact which 

 calls down the criticisms of those astronomers 

 who believe the new silvered glass mirrors of 

 Foucault to be much preferable. The former, 

 it is claimed, reflect less light, are much heav- 

 ier, and, when their polish is lost, do not ad- 

 mit of reparation, except at a great expense, as 

 the repolishing is nothing short of refiguring, 

 which is a costly and delicate operation. Ee- 

 silvering a glass mirror costs little, and does 

 not demand unusual skill. The point of sus- 

 pension of the Melbourne telescope-is near the 

 mirror, on account of its immense weight ; and 

 in front of this point the telescope stretches 

 forward to about 30 ft. of open lattice-work, 

 made of bands of elastic steel. It is thought 

 that heavy winds must produce considerable 

 motion in so long an instrument. The tele- 

 scope is on Cassegrain'splan, with the eye-piece, 

 as in the Gregorians, at the bottom, and very 

 convenient for use. The adjusting appara- 



