12(j Anah/sis of Scientific Books. 



to a strong light, the retina from its transparency allowing it to 

 pass through without injury." " That the nigrum pigmentum is 

 not necessary tor vision, but only provided as a defence against 

 strong light, is proved by its being darker in the Negro than in 

 the European, and lighter in fair people than in dark, and there- 

 fore lightest in those coimtries farthest removed from the effects 

 of the sun." " In the monkey it is dark, and in all animals 

 that look upwards. In all birds, exposed to the sun's rays, it is 

 black. In fishes, the basking shark which lies upon the surface 

 of the ocean, has a nigrum pigmentum. The turbot and skate 

 which lie upon banks of sand in shallow water, have nigrum pig- 

 mentum. In all ruminating animals and birds of prey, there is 

 a broad tapetum at the bottom of the eye. The owl, that never 

 sees the sun, has no nigrum pigmentum." " The coup dc soleil 

 I attriljute to the scorching cti'ccts of the sun's rays upon the 

 scalp. The Egyptian ophthalmia I consider to be the effect of 

 the sun's rays, and the glare of reflected light." 



ii. On the Magnetic Phcenomcna produced hij Electricity, in a 

 Letter from Sir H. Davy, Bart., F.R.S., to W. H. Wol- 



LASTON, M.D., P.R.S. 



The intimate connexion, if not the identity, of magnetism 

 and electricity, has long been suspected, and indeed partly de- 

 monstrated; the recent discoveries of M. Oersted have com- 

 pletely proved the subsisting relation of these powers of matter, 

 and have set a number of persons to work at the repetition and 

 extension of his inquiries. In our last Number we have trans- 

 lated M. Biot's communication to the Parisian Academy of 

 Sciences upon this subject, and upon a former occasion (vol. x, 

 p. 361,) our readers have been presented with an outline of the 

 recent discoveries connected with it. Since the date of this 

 paper. Sir Humphry has himself extended his interesting experi- 

 ments and observations ; and in July last, he read a second me- 

 moir to the Royal Society, in which much that is left incomplete 

 and undetermined in the paper now before us, is perfected and 

 cleared up ; of this we shall give an account in due course. 



iii. Communication of a singular Fact in Natural Historij. By 

 the Right Hon. the Earl of Morton, F.R.S. 



iv. Particulars of a Fact nearly similar to that related by Lord 

 Morton, by Daniel Giles, Esq. 



Under these mysterious titles the following facts will be 

 found. Some years ago Lord Morton, desirous of domesti- 

 cating the quagga, endeavoured to procure a male and female 



