SCIENTIFIC SUMMARY. 
421 
sun ; cf>, the radius vector of Venus. Then the horizontal refraction of the 
atmosphere of Venus was found from the equation, 
By this formula Madler found the horizontal refraction of the atmosphere of 
Venus to be 43'-7. 
Strangely enough, the Astronomer Royal to whom Madler sent his result, 
and who communicated an account of it to the Astronomical Society, 
detected no flaw in the formula, nor did the editor of the “ Monthly Notices,” 
who published it. Prof. Lyman, also, of Yale College, Conn., U.S., 
employed the formula unchanged to reduce his measures of the prolongation 
of the cusps, as observed with a 9-in. refractor, in 1866 and 1874, getting 
45' ‘3 and 44'*5 for the horizontal refraction of the planet’s atmosphere. We 
may learn from this how necessary it is to examine carefully every formula 
one may have occasion to employ in scientific work, no matter what 
authorities may have given it their sanction. For, after all, the formula was 
wrong. Mr. Neison, in a Paper recently read before the Astronomical 
Society, says, u A note by Mr. R. A. Proctor, in the 1 Astronomical Register ’ 
(October 1875), induced me, as soon as I had the leisure, to examine this 
formula of Madler’s, when it was at once apparent that as it had been em- 
ployed by Madler and Lyman it was defective. Instead of the angle V, or the 
angular distance between the centres of the sun and Venus, as seen from the 
earth, which they had used, they should have employed the supplement of 
the angle between the sun and earth, as seen from Venus. In consequence 
of this error, the value which they have deduced from their observations for 
the horizontal refraction of the atmosphere of Venus is incorrect.” Making 
the correction indicated by Mr. Proctor, 'Mr. Neison obtains as the mean result 
of Madler’s observations 54'*43. The four observations by Lyman in 1874 
give 56'*34, 51'*54, 54 /, 63, and 5F*49, the mean value, 53'‘50 agreeing closely 
with the result obtained from Madler’s. Combining both series with Lyman’s 
results in 1866, Mr. Neison obtains 54' ‘65 as the probable horizontal refrac- 
tion of the atmosphere of Venus ; whence we may infer that the surface 
density of the atmosphere of Venus is not far on either side of P892 times 
that of the earth’s. 
Imagined Specidar Reflexion from Surface of Venus. — Mr. Brett, the 
landscape painter, who some time since startled the astronomical world by 
stating that he had seen the solar corona when there was no eclipse and 
without telescopic aid, has lately made another remarkable discovery, stating 
in a paper read before the Astronomical Society (but cruelly suppressed by 
the editor), that he had detected unmistakable specular reflexion from the 
surface of Venus. Capt. Noble was led to investigate the question. “His 
first step was to examine the planet with the telescope in the usual way, 
and no signs of specular reflexion could be seen. He then, using a power of 
255, interposed a graduated shade of dark glass. The first part to fade away 
was, of course, the fainter portion near the termination, then the cusps, and 
finally the bright part of the limb ; not the slightest sign, trace, or indica- 
tion of specular reflexion being visible.” 
Photometric Experiments upon Venus. — Mr. J. J. Plummer has made 
.some photometric experiments upon Venus by a new and ingenious method, 
where sin \Js = sin V, sin x. 
