BLAKE — CUELONTAN SCUTES FROM THE STONESflELD SLATE. 183 
a than in the intervening periods. Now Tyndall speaks of the earth 
receiving but the t yo oo'oooo o P''^^^ of the solar rays, and therefore it 
f might be said that tlie falling in of the earth would only reduce the 
temperature of the earth by that part of a degree ; but, on the other 
t hand, we should have to consider what influence such an event would 
1 produce if the point of collision and obscuration was in a direct line 
i with the earth. In such a case the direct light- and heat-rays would 
1 be shut off*, and although compensated for in a great degree by the con- 
vergence of the surrounding rays in the great flood of light coming 
3 away from the sun, a considerable effect might be produced on the 
t temperature of the earth. Of what effect might be produced we have 
t perhaps some examples in the actual eff'ects produced by sun-spots. 
Single spots often appear of dimensions equal to and exceeding that of 
3 our earth, and periodically we have numerous congeries of spots of 
I sufficient importance to produce disturbances at any rate of the mag- 
; netical conditions of our globe if not indeed to produce anv distinctly 
f perceptible diminution of temperature. That the latter eff'ect might 
1 not be readily determinable in the converging or ffuctuating states by 
our atmosphere is by no means sur])rising; but it should be borne in 
' mind that Arago and other astronomers have asserted and attempted 
t to prove that the maximum periods of sun-spots are regular decades 
r of Ider years. Such minute changes as tliose produced by these 
, minor differences in the amount of materials in actual conffagratiou 
r would have had little eff'ect on the general climatal temperature of 
' our earth, but if a differeuce, no matter how small, could in this or 
I any other way be proved, it would be a basis for real conclusions on 
; the subject. There are, however, five other ways in which the solar 
rays might aff'ect the general climatal conditions of the earth. 1. The 
f mass of the sun being larger or smaller would radiate more or less 
heat accordingly. 2. There might be maximum and minimum periods 
f of Conffagratiou. 3. The extent of the earth's atmosphere might inffu- 
; ence climatal condition by the conversion by friction of the light rays 
into heat, just as light rays falling on a black surface are arrested, 
annihilated, converted into heat, which they are, and on the same 
principle that a falling bullet striking the ground has its velocity or 
motion changed into an equivalent of heat. 4. A former higher and 
lower rate of rotation of our own globe would h'lve important effects 
upon the climatal conditions and on the vt-getation and life of our 
planet. 5. Variations in the dimensions of the orbit of the earth. 
{To be continued.) 
ON CHELONIAN SCUTES FROM THE STONESFIELD 
SLATE. 
By C. Caeter Blake, Esq. 
In the British Museum there are several specimens of " papiliona- 
ceous" flattened bodies exhibiting six or more concentric lines ra- 
