NOTICES OF BOOKS. 213 
occur in the lens instead of in the vitreous humour. The statement on p. 43, “that 
water never looks as deep as it really is : a pond that looks only three feet deep is 
really four feet deep ” is far too general : the pond only appears shallower if it be 
looked at obliquely ; if, as in the figure given, the line of sight be perpendicular to 
the surface of the water, there will be no refraction, and the bottom will not 
appear to rise. We do not know whether Miss Johnson really believes the story 
about the 30,000 luminous worms in every cubic foot of thirty miles of ocean, but 
we will hope the children did not. A more serious objection is the suspicion that 
many of the experiments described were never really performed ; the Manchester 
people must have very powerful circulations if the crude pulsometer figured on p. 
48 gave any approach to the indication shown ; the vibration of the beams of light, 
if it occurred, was probably due to the shaking of the operator’s hand. 
When, however, we come to consider how far the method of teaching was 
successful, we find that the results were most satisfactory ; even as early as p. 220 
the author tells us that both Edmund and Ernest have been converted into “ little 
philosophers already : ” we hoped to follow the development of these prodigies of 
sagacity to the end of the volume, but unfortunately their names do not appear in 
the last chapters, so we fear they must have been promoted to a higher sphere, or 
perhaps did not return from the excursion to the moon to which the class were 
treated. No doubt the excellence of the results was due to the interest Miss 
Johnson took in each member of her flock : she knows them and calls them all 
by name — with irritating frequency. Judging by the numerous names scattered 
