734 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 : 



It is a singular fact that when we can find out how any thing is done, our 

 first conclusion seems to he that God did not do it. No matter how wonderful, 

 how beautiful, how intimately complex and delicate has been the machinery 

 which has worked, perhaps for centuries, perhaps for millions of ages, to bring 

 about some beneficent result, if we can but catch a glimpse of the wheels, its 

 divine character disappears. (" Darwinism in Morals," in Theological Review, 

 April, 1871.) 



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 confi- 

 dently 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 reasona- 

 bly) be dissevered from faith in an Ordainer, which is the basis of 

 religion. 



> 



VISUAL IMAGES IN DAKKNESS. 



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 pass- 

 ing notice. 



In the first place, I must beg permission to quote Sir John's own 

 words respecting the most frequently-occurring forms those possess- 

 ing perfect geometrical regularity : 



" I find them," he says, "to be formed in darkness, and, if the dark- 

 ness 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- 



