HARD WICKE'S SCIENCE- G OSSIP. 



187 



the scale corresponding to the depth of blue would 

 indicate the number of dust-particles in a cubic inch 

 of air. Of course this "detector " is new, but it is 

 simple, and it will likely be so improved that sanitary 

 officers can use it conveniently, and with a fair amount 

 of accuracy. By an india-rubber tube, air can be 

 taken into test-tube from any part of a room, or 

 passage, or drain, and tested without any trouble. 

 Mr. Aitken, in the course of his observations, was 

 obliged to come to a conclusion quite opposed to 

 one's expectations. A window is not an unalloyed 

 boon as regards the purity of air in a room. In every 

 case tested, he found that, when gas is burning, the 

 air near the window is very impure. There is a 

 polluted down-current of air from the ceiling. This 

 is caused by the cold air on the window sinking and 

 drawing down with it the polluted air near the 

 ceiling. The impure air is brought down to the level 

 of the face, and the lungs get the benefit of the 

 pollution at every inhalation of air. This is of course 

 most noticeable by the instrument when the windows 

 have no blinds or shutters. It is, however, an un- 

 fortunate fact, discovered by the "detective." 

 Though an open window supplies pure air, a shut 

 unprotected window does much harm, by bringing 

 down the polluted air which otherwise would remain 

 near the ceiling. 



Doubtless this matter is only in its infancy ; much 

 yet requires to be done to mature the inquiry. 

 Flowers are cultivated as well as fruits ; and im- 

 portant results are, it is to be hoped, yet in store by 

 the improvements on these two remarkable instru- 

 ments. Quite a new field is open for scientific 

 inquiry in connection with sanitary reform. Who, 

 till the other day, would ever have conceived that a 

 preparation of the thyroid gland of a sheep could be 

 instrumental in removing from a sufferer the awful 

 close that usually attended the indescribable disease 

 of mysccedema? Then sneer not at the initiative 

 stage of these marvellous products of an inventive 

 brain ! 



J. G. McPherson. 



SUGARING FOR MOTHS IN JUNE. 



WHEN the nights of mid-June were too hot for 

 sleep it was an agreeable change, after the 

 burden and heat of the day, to sally forth into the 

 Worcestershire woods in order to sugar for moths, 

 and amid such pleasant surroundings, the self-allotted 

 task became an all-absorbing occupation. An ideal 

 spot came handy for sugaring operations, where a 

 green drive intersected a thick wood, and open 

 glades here and there on either side led into the 

 inner fastnesses, through which the moths came forth 

 at the fall of eventide. I have observed that the 

 noctua and other night-flying kinds of moths 

 habitually find an exit into the more open spaces, 



through such openings having, so to speak, their 

 regular lines of flight, with which it is well to be 

 familiar. Suitable trees flanked either side of the 

 main drive, and experience soon revealed the best 

 trunks to select for the purpose of sugaring. Thus, 

 the buff arches (Thyatira derasa) and the peach 

 blossom (T. batis) came especially to one or two 

 trees through one particular opening of the woods, 

 and the first-named proved restless, rarely settling 

 well on the sugar. Both are "noisy " moths, beating 

 their wings to pieces in a pill-box, therefore, it is 

 my practice to kill them at once in the cyanide bottle, 

 in order to secure good specimens. The peach 

 blossom is really an exquisite moth with the delicate 

 patches of pale coral hue on the outer wings. There 

 is an imitative faculty connected with this moth, 

 which possibly entomologists have recognised. At 

 rest upon a tree, the ground colour of the wings is 

 lost, while the pink spots are strangely suggestive of 

 a fungoid growth upon the bark. Several times I 

 nearly failed to detect the moth at all, which, by the 

 way, has been plentiful with us in Worcestershire 

 this year, at least three dozen coming under my own 

 notice in June and July. A single specimen only of 

 the figure-of-8 moth have I seen taken with sugar ; 

 though somewhat scarce, I believe it to be one of the 

 representative Worcestershire species, perhaps more 

 being taken in autumn pupa-digging than in the 

 perfect stage of existence. Another fellow that has 

 interested me deeply is the coronet moth {Acronjeta 

 ligmtri), which I have absolutely failed to detect from 

 silver-grey lichens on the trees — the imitation is com- 

 plete. 



Certain moths swarmed in my particular wood, 

 being so prolific as to become a real nuisance. 

 Amongst these I may mention Agrotis exclamationis, 

 Triphana promiba, Aplecta ncbiilosa, and Miana sp., 

 the latter looking black upon the trees. The orange 

 moth (Angeronia prunaria), apparently not common, 

 was in perfect condition, and a solitary specimen of 

 the blotched emerald {Phorodesma bajtdarid), attached 

 to a blade of grass, had just come forth in an 

 accommodating manner from the pupal sac. Many 

 very beautiful specimens of the satin moth [L. salicis) 

 I took from a weeping poplar, simply picking the 

 snow-white creatures from the leaves, both males and 

 females, together with the yellow-haired pupae, and 

 the handsome caterpillars. There were fully a 

 hundred on the one tree, and one of the females at 

 once proceeded to lay eggs in a match-box. It is a 

 noteworthy fact that only on this one tree can I ever 

 find the satin moth. The striking larva; of the puss 

 moth have the same habitat each year. The pupa 

 cases, in the interstices of the bark* I can never 

 discover until they are evacuated. The gold-tail I 

 caught in the net shortly before dark, and also got 

 somewhat severely urticated by the larva crawling on 

 my neck. Amongst the noctua on the sugar the 

 purple clay (N. bnitmea) predominated. The small 



