i5° 



HARDWICKE'S SCIENCE-GOSSIP. 



However, these small criticisms which I shall 

 venture on must not be taken as of any particular 

 consequence. Where there is so much to praise and 

 so little to find fault with, they must be taken simply 

 as a proof that I have read the book carefully from 

 cover to cover, and not, as is too much the habit of 

 reviewers, cut the leaves and smelt the paper-knife. 



Various methods of observing the sun are then 

 described, and a most necessary warning given 

 against looking at our great luminary through an in- 

 strument of this small aperture without using a screen 

 of coloured glass over the eye-piece. Even these dark 

 screens are not a complete protection to the observer, 

 for I have had dozens of them sent to me for renewal, 

 in which the heat has cracked them, and very many 

 in which it has melted the centre of them. An 

 excellent precaution is to use two pieces of plane- 

 coloured glass in the shade head instead of one. I 

 have never known two such coloured screens to be 

 broken at the same time. If one breaks it is always 

 the one next the sun and furthest from the eyes, and 

 this should be replaced without delay before using 

 it again. But the method of viewing the sun by 

 projection (that is throwing its enlarged image on a 

 sheet of white paper placed at a distance from the 

 telescope) which is recommended is better, though 

 this will not enable nearly so much detail to be seen 

 as can be made out with a proper solar eye-piece. 



The moon is then described and a map of the full 

 moon given, together with a key to the map which 

 contains a list of 400 of the principal objects on its 

 surface. 



Next there is an excellent description of the occul- 

 tations of stars and planets by the moon, and the 

 method of observing them. After the moon come 

 the planets, the author waxing eloquent as he 

 describes Venus and Mars. Respecting the last- 

 mentioned planet I may say, in passing, that only an 

 observer whose visual power has been well trained, 

 and is above the average, will see as much of Mars 

 as is shown in the engraving given of the planet with 

 a telescope of three-inches aperture. The account of 

 Jupiter and Saturn and their satellites may be also 

 commended, though the drawing of Saturn has 

 evidently not had justice done to it by the engraver. 



After a brief account of the planets Uranus and 

 Neptune, there are instructions for drawing the 

 planets, particularly Jupiter and Saturn, and the 

 book finishes with nine chapters, each supposed to 

 contain an account of observations which may be 

 made on one night, of the stars and nebulae. In 

 these chapters the principal double stars are well 

 described and illustrated with some excellent little 

 engravings, the best I have seen of these difficult 

 objects. 



In the preface Captain Noble deprecates com- 

 parison between his book and other books of the 

 same kind ; but he need fear no such comparison. 

 There are books written with a similar intention to 



his, but not one which will, to an equal degree, 

 answer the same purpose. There are again more 

 ambitious works, some of which as catalogues of 

 objects, almost defy criticism. Yet not one of these 

 describes so simply and clearly the smallest telescope 

 which can with advantage be used by the tyro, and 

 the immense number of exquisitely beautiful and 

 interesting objects which may be viewed with such, 

 an instrument. 



John Browning. 



NOTES ON THE PROTECTIVE COLOURING 

 AND HABITS OF LEPIDOPTERA. 



By W. Hakcourt Bath. 



THE subject of mimicry in connection with 

 Lepidoptera is a very interesting one, but I 

 believe very little patronised by the majority of 

 entomologists. To study it more closely would no 

 doubt reveal many hitherto unknown points in the 

 economy of a great number of species. 



There is no necessity to go abroad to obtain 

 examples of mimicry ; we have scores of interesting 

 examples in our own country. A walk through the 

 fields and lanes anywhere during the summer-time 

 would afford a very lucrative field for any observant 

 eye. 



The larvae of most of the Geometrae afford many 

 excellent examples of protective colouring and habits. 

 The long stick-shaped sombre-hued caterpillar of the 

 swallow-tail moth ( Uroptayx sambucata) in particular 

 minutely resembles a twig when stretched out at full 

 length — in which position it often remains motionless 

 for hours, and thus successfully evades the prying 

 eyes of the Paridae and other insectivorous birds 

 which are continually on the look-out for dainty 

 morsels in the shape of grubs. 



A great number of caterpillars which are greenish- 

 coloured find abundant protection in their resemblance 

 to the herbage upon which they feed. The green 

 larva of the small white butterfly {Pieris rafcc), for 

 instance, is extremely difficult to discern among its 

 food plants, as it usually, when at rest, lies parallel 

 with the leaf-veins and stalks of the cruciferous 

 vegetables upon which it feeds. 



The beautiful caterpillar of the emperor moth 

 {Satumia pavonid) affords another excellent example 

 of protective colouring ; the pink and yellow spots 

 with which it is adorned minutely resembling the 

 flowers of its pabulum heath. Many other cater- 

 pillars which are not so wonderfully endowed by 

 nature with protective colouring are provided with 

 other means for baffling their foes. Some are 

 provided with spines, as in the peacock ( Vanessa w), 

 and others with long hairs, as is the case with the 

 tiger moth (Arctia caja), such being greatly disliked 

 by the majority of birds. 



