Mr. Henwood on the opposite Walls of Cross-veins. 443 
strongly attracted my attention was, that the intermediate 
space between the two bows was of a different shade, being 
more the colour of Indian ink than neutral tint, and was con- 
siderably deeper in tone than the portion of cloud either 
within the primary or without the secondary bow. The whole 
together had the effect of a broad circular riband, bordered 
on each side with the prismatic colours, The alteration in 
the tint of the cloud was so perfectly coincident with both the 
bows, as to leave no doubt of the necessary connexion be- 
tween the two phenomena, 
I cannot suppose it to have been an accidental accumula- 
tion of cloud in that particular region, but imagine it to have 
some connexion with the phenomena of light and reflexion 
or refraction. This singular effect continued nearly as long 
as the rainbows were visible, viz. about 4 or 5 minutes. 
The masses of cloud seemed to accumulate towards the 
centre of the circle, and also at some distance on the outside 
of the secondary bow, though this probably was only an acci- 
dental coincidence, but in effect it was as though the clouds 
had been partially withdrawn from both sides of the double 
band, and collected in the space between the two bows. 
Victoria Park, Manchester, April 15, 1843, 
LXXVII. On the Appearances and Relative Positions of the 
Rocks and Veins which form the Opposite Wails of Cross- 
Veins. By W. J. Henwoon, C.ZE., F.RS., F.G.S., 
M. Inst. C.E., Member of the Geological Society of France, 
of the Royal Geological Society of Cornwall, §c. 
{Continued from p. 384.] 
Il. L=t us now apply to the intersections of two or more 
lodes, or other veins, by the same cross-vein, the same 
laws which have been assumed to prevail when there is but a 
single intersection. 
(1.) In the event of a horizontal movement, any number 
of veins contained in the mass of rock displaced, should be 
always heayed to the same distance in every instance, and 
for the same extent at all levels: but this result never occurs 
(a, d, €, fy By hy i, m, &c.). 
But, although a horizontal motion will not accurately apply, 
as its results will not agree with the order observed, it will, 
nevertheless, produce effects bearing a nearer resemblance 
to the facts than those following motion in any other direc- 
tion. In short, where two or three lodes are intersected by 
the same cross-vein, 70°2 per cent. of the total number are 
