3 MAY 1930, Page 21

In Modern Sunlight (Murray, 7s. 6d.) Mr. Leonard V. Dodds

tells us of all kinds of curious and important uses to which artificial rays may be pid todiscover, for instance; the impu- rities in paint ; to reproduce the almost-vanished marks of

fossils on rocks ; and, more marvelloui still, to photograph writing on parchment which has been erased and written over ; to test the freshness of eggs ; to sterilize water ; and to improve the health of animals. Mr. Dodds declares that when

pigs were experimented' u-pon, they' crinie of their own accord and lay down under the iiiercury-vapour lamp! The irradia- tion hens has greatly improved their 'egg-laying qualities.

Even bees, under this stimulus, have been known to hum in their hive as if the mid-day sun were shining, and to build many more cells than in a non-treated hive under otherwise exactly similar .conditions. Racehorses have long been treated with ultra-violet rays. But Mr. Dodds is even more interesting in his' description Of what this' new branch Of science may do for litimair heir* : We have here a. guide to heliotherapy in all its aspects, suitable for the general reader as Well as those more

specially interested in the subject.

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