HARDWICKE'S SCIENCE-GOSSIP. 



227 



it or turn either of the glasses the wrong way, so 

 as to subvert the principle on which it is made. 3 



"'I like this sort of test better than the diagonal 

 lines on the brassica. The name of Herschel carries 

 with it weight and authority, but I must give full 

 loose to my scepticism in the meantime, and assert 

 that microscopes may be very good, and perfectly 

 to be depended upon for making discoveries in all 

 the ordinary branches of natural history and micro- 

 scopic research, which will hardly show any of 

 these precious things you have set up as tests, a 

 plague upon them ! Are we to be eternally bored 

 to death with the dust of butterflies' wings and the 

 scales of beetles ? For my part, I don't value them 

 a rope's end ! ' " 



Mr. Putty politely tells him that he ought to be 

 made to appreciate the uses and properties of a 

 rope's end at their full value— — " 'nevertheless I 

 myself will so far agree with you that I consider the 

 whole family of lined tests as very exclusive sort of 

 objects. It is very difficult to find others requiring 

 the same penetrating and defining power. I think 

 hardly any reasonable person can refuse to admit as 

 proper tests for all microscopes, of what nature or 

 kind soever they may be, the researches in which they 

 are to be employed : such are the minutiae of a fly's 

 foot, the serratures on a human hair, the little pits 

 on a mouse's hair, the tissue of the moss Hypnum ; 

 and to these must be certainly added the eyes of 

 several animalcules. If an instrument cannot show 

 these you would reject it as unworthy of confi- 

 dence?' 



"'My dear sir, you now begin to talk like a rational 

 being. I cordially agree with you : all these things 

 single lenses will show in perfection. Do you know 

 I had such satisfaction the other day in showing a 

 young puppy the eyes of a wheel animalcule with a 

 single equi-convex lens. He thought, forsooth, to 

 have come over me with his thingamy, his hang-his- 

 scope, as I think he called it.'" 



All Mr. Putty's arguments are of no avail ; and 

 as a last resource he asks him to look at a podura 

 scale in the engiscope, if he is not afraid. 



" 'Afraid, indeed, a likely joke !' 



"'Can you say you have seen this object as well 

 in your single, or I will say in your compound 

 magnifiers ? Say, on your honour ! ' " 



" 'I cannot say upon my honour that I have seen 

 the lines so dark and so decidedly made out ; but 

 the circumstance is easily accounted for by the 

 superior darkness of the engiscope. But I told you 

 before, engiscopes cannot be trusted for exploring 

 unknown objects or making discoveries : the whole 

 is an illusion. I see your patience is nearly worn 

 out: I will not plague you any more, except to 

 view the diagonal lines on the brassica in the in- 

 strument which discovered them — the reflector of 

 Amici. i They are shown so decisively in this 

 instrument that it would be as reasonable to doubt 



their existence as that of ruled lines in a copy 

 book. Doublets and achromatics sometimes show 

 them, sometimes not ; but the reflectors never con- 

 ceal the truth. Moreover, observe the perfectness 

 of the longitudinal lines. No dots /' " 



Mr. Oldbuck says that it would naturally show 

 them darker, the reflecting being still darker than 

 the refracting engiscope. 



After this, Mr. Putty found it would be no use 

 to make any further attempt to convince Mr. Old- 

 buck of the superiority of the engiscope over his 

 favourite single lenses. 



We have given these extracts from Dr. Goring's 

 amusiug chapter on trying microscopes and engi- 

 scopes, as it very accurately represents the capa- 

 bilities of microscopes forty years ago, and the kind 

 of objects that were considered as tests for the 

 resolving powers of refracting and reflecting objec- 

 tives. We are enabled to see what the achromatic 

 microscope could do in its infancy, on objects that 

 would now be considered useless as tests for even 

 the cheapest achromatic of the present day. 

 {To be continued.) 



THE LEPIDOPTEBA OF 

 NEW FOREST. 



THE 



IN the December number of Science-Gossip, an 

 inquiry was made for a good work on the New 

 Forest. I would advise your correspondent to pro- 

 cure " The New Forest Handbook, Historical and 

 Descriptive," by C. J. Phillips (Southampton, 

 Gilbert).* There are chapters on the botany and 

 ornithology, and an extremely interesting one on 

 the entomology, of the district, by my friend Mr. 

 Corbin. There is also a capital map designed by 

 Mr. J. H. Roberts, one of the Forest surveyors, 

 especially for the work. The price is nominal, viz. 

 Is. 6d. 



The few remarks following are written with the 

 hope that entomologists will be induced to con- 

 tribute notes on the Lepidoptera, &c, of other 

 celebrated localities, such as Epping, for the pur- 

 pose of comparison. I am indebted for the number 

 of the species to J. R. Wise's admirable book on 

 the New Forest. 



Out of our short list of seventy species of Diurni, 

 forty-six have been taken here, and it is one of the 

 very few spots where that glorious variety of the 

 female Paphia, Valezina, is to be obtained ; boasting 

 also such local insects as Aporia cratagi, Hesperia 

 paniscus, and Leucophasia sinapis, of which my 

 brother and I have taken there a goodly series. 



In the Heterocera we find, in the Nocturni over 

 seventy species, in the Geometers more than one 

 hundred and eighty, and in the Noctua; nearly two 



May be had also of G. B. Corbin, Ringrwood. 



