182 , REPORT—1857. 
distributed) would converge on it equally from all quarters. But the earth, 
in fact, being in motion with a velocity half that of the average velocity of the 
meteors, it encounters nearly two-thirds of the number on the side towards 
which it is moving. t 
II. A considerable series of results has been investigated by M. A. Poey, 
respecting the colowrs of luminous meteors, derived from extensive sets of 
observations collected by M. Ed. Biot from those made in China from the 
7th century .c. to the 17th a.p,;—those collected in the Reports of the 
British Association ;—and those made at Paris by M. Coulvier-Gravier. 
Among these generalizations we may remark the following :— 
In the Chinese observations meteors of simple primztive colours are very 
rare, the great majority being of compound tints; in the European observa- 
tions the reverse is the case. 
The Chinese observations show a remarkable constancy of tints during a 
long period of years, when an equally constant but different scale of colour 
prevails ; and this for several successive periods. 
Cases of complementary colours in the body of the meteor and the train, 
or fragments, are often noticed. 
Changes of colour during the course of the meteor are observed, being 
most usually from wife near the zenith to blwe near the horizon, but some- 
times from white to red. This, the author observes, agrees with the law of 
M. Doppler, that a luminous body moving éowards the observer will change 
its colour from white, in suecession to the violet end of the spectrum ;— 
moving from the observer, to the red. This law, he states, is especially con- 
firmed by the Paris observations. He remarks on the necessity for attend- 
ing to personal differences in observers’ estimate of colour; a remark fully 
confirmed by the great contradictions existing in the descriptions of the 
colour of many of the brightest meteors, at the same time and place, by dif- 
ferent observers. 
He gives the results of the various observations cited, in tables exhibiting 
the number of meteors of each tint for each month; and adds others of 
meteors arranged under several heads, of physical peculiarities. 
The details are given in the Appendix No. 4. 
III. One point of the highest interest and importance towards forming 
any sound theory of meteors, is the estimate of their actual size from their 
apparent diameters and calculated distance. In all the results usually given 
this calculation is made on acknowledged geometrical principles, assuming 
that the apparent disk is the real one, diminished only by the effect of 
distance. 
Prof. J. Lawrence Smith of the U. S. has adduced some very remarkable 
optical experiments to show the entire fallucy of any conclusion from the 
apparent diameter of a highly luminous or incandescent body seen at a 
distance. 
These experiments exhibit a singular apparent enlargement of the visible 
disks of intensely luminous bodies of known size, when observed successively 
at distances of 100 yards, of a+ mile, and 4 mile; at which distances re- 
spectively, for example, the body of electric light of carbon points (actually 
0°3 inch diameter) appeared 4, 3 times, and 34 times the diameter of the 
moon ; and other incandescent bodies in a similar proportion dependent on 
the degree of ignition, 
These results seem dependent on some optical or ocular cause, of greater 
energy than we can ascribe readily to simple irradication ; but in a rough way 
they admit of some degree of verification by looking at a row of street lamps 
seen nearly in a line from the eye, the apparent diameters of which do not 
