94 
POPULAR SCIENCE REVIEW. 
Tlie Astronomer Royal’s result is, that the moon’s angular diameter 
hitherto received is too large by 2" ; Mr. De la Rue’s that it is too large by 
2' 15". This quantity must be looked upon in its entirety as a telescope 
fault, or we must attribute part of it to the effect of the lunar atmosphere- 
The Astronomer Royal remarks that if the whole be attributed to such a 
cause, it would imply a horizontal refraction of 1", or about of the 
earth’s. This would indicate an atmosphere discoverable in no other way. 
Rut Luna may console herself ; she is to have a beautiful map. At the last 
meeting of the Lunar Committee of the British Association, it was decreed 
to prepare at once a skeleton map 100 inches in diameter, from Mr. De la 
Rue’s photographs, reduced to a state of mean vibration ; and this map is to 
be served out in zones of 1° wide to all who will promise to help forward the 
complete work. 
The mention of Mr. De la Rue’s photographs reminds us that Mr. De la 
Rue now generously confesses himself beaten by Mr. Rutherford in the 
matter of lunar photography, a night of surpassing definition having enabled 
the American physicist to secure a faultless negative. 
Mr. Dane’s admirable drawings of Mars are to appear in the Monthly 
Notices for January. 
The small planets now number 85, the discovery of one of 9y mag. having 
been made by Mr. James Watson, of the Ann Arbor observatory, on the 9th 
October. 
To come to Comets, those of Biela continue to elude too many of our 
observers, in spite of Mr. Bishop’s widely-circulated ephemerides. It 
appears probable that the lines of perihelion passage of the two Biela comets 
in 1866 will fall on January 27 and January 29, or nearly so, G. M. T. 
It would seem that they have considerably changed in brightness. 
In the Comptes Hendus for 27th November, M. Liais returns to the 
question of the earth’s passage through the tail of the comet of 1861. His 
examination of the problem is conducted very carefully, and his results are 
as follows : — 
“ The breadth of the comet’s tail, judging from the angle of 3° 30', which it 
subtended on June 19, was equal to the fraction 0 '02334252 of the earth’s 
orbit, or 878,000 French leagues (of 4 kilometres). The distance of the earth 
from the point of contact between its orbit and the axis of the tail at my 
station, Rio Janeiro, at 6h. 12m. 10s., on June 30, in the morning, was 
equal to 0*0087598 of the same radius. As the angle between the paths of 
the earth and comet was almost a right angle, 91° 2' 54", the distance of the 
earth from the axis was therefore 329,000 French leagues. Thus, at this 
moment the tail inclosed the earth, which was plunged into it to the depth of 
110,000 leagues.” 
We learn from the Anniversary Address delivered by the President of the 
Royal Society, that the good people of Melbourne, although they have 
rejected Mr. Lassell’s 4 feet speculum reflector, are still to have a reflector by 
Grubb, of Dublin. We venture to think that this decision will yet be 
regretted. The reflector is, we believe, to cost <£5,000. Mr. Lassell’s, 
although, teste Struve, is no better than the Poulhower 16-inch refractor, is 
doubtless as good as, in the nature of things, Mr. Grubb’s will be. Now a 
speculum has two unfortunate habits ; -it has a tendency to bunch stars into 
