THE POPULAR SCIENCE MONTHLY.
the present day that hardly a discourse can be pronounced or an investigation prosecuted without reference to them. I suppose that the views here taken are little, if at all, in advance of the average scientific mind of the day. I cannot regard them as less noble than those which they are succeeding. An able philosophical writer, Miss Frances Power Cobbe, has recently and truthfully said:
I agree with the writer that this first conclusion is premature and unworthy; I will add deplorable. Through what faults or infirmities of dogmatism on the one hand, and skepticism on the other, it came to be so thought, we need not here consider. Let us hope, and confidently expect, that it is not to last; that the religious faith which survived, without a shock, the notion of the fixity of the earth itself, may equally outlast the notion of the absolute fixity of the species which inhabit it; that, in the future, even more than in the past, faith in an order which is the basis of science will not (as it cannot reasonably) be dissevered from faith in an Ordainer, which is the basis of religion.
|VISUAL IMAGES IN DARKNESS.|
THERE is a chapter in Sir John Herschel's volume of "Lectures on Scientific Subjects" which treats of certain peculiar forms of ocular spectra, under the above title.
The spectra here alluded to—those which present themselves to us, independently of the will, in darkness or when the eyes are closed—are familiar to us all; but it appears to me that the subject has certain bearings which have been hitherto overlooked, and which merit a passing notice.
In the first place, I must beg permission to quote Sir John's own words respecting the most frequently-occurring forms—those possessing perfect geometrical regularity:
"I find them," he says, "to be formed in darkness, and, if the darkness be complete, equally with open or closed eyes.
"The forms are not modified by slight pressure on the retina, but their degree of visibility is much and capriciously varied by that cause. They are very frequent; in the majority of instances, the pattern pre-