SCIENCE-GOSSIP. 



23 



SiNm.NU-I'l.llcs, — The folliiwing note, extracted 

 from my natural history diary and bearing on the 

 singing or hmnming of Sjrphidae while at rest will 

 perhaps prove of interest to \Ir. Edward H. Robert- 

 son (S. G., Vol. V. N.S., p. 345) and other readers of 

 SciENCE-Gossii'. November 14th, 1S96. — In August 

 I had Butler's " Household Insects," for the first 

 lime. In it I found recorded, on the strength of the 

 observations of some other observer or naturalist, 

 the fact of a large species of SyrpliKs indulging in a 

 humming or singing when seated on the ground on 

 stones whilst at rest. This record at once recalled 

 to my memory the fact that I had at least twelve 

 months previously been surprised to hear a uniform 

 shrill, high-pitched humming or singing close to my 

 ear, whilst I was seated on a rail beneath the trees at 

 the bridge crossing the burn in the Crofts at Killing- 

 worth. It was altogether different in tone from the 

 humming of the numerous Syrphi or "hoverer- flies,'' 

 which were soaring and darting about in the 

 bright and warm sunshine of the afternoon. 

 I thought the sound must emanate from some of them. 

 Still, the uniform]}' equal tone, shrill and somewhat 

 gnat-like hunmiing or singing, appeared to be quite 

 close to my ear, but on turning my head very gently, 

 I could find no Syrpkiis, or other insect, hovering 

 there, whence the sound appeared to proceed. I then 

 gently raised the hat from m_\' head, and as gently and 

 slowly lowered it to the level of m\' eyes, when the 

 musician stood, or rather sat, revealed on the brim of 

 the hat. It was a black-and-yellow Syi-phiis of the 

 same size as Syrphiis ribcsii, and was very probably 

 that insect. Its wings, though closed, were not at 

 rest, but were rapidly \ibrating ; so rapidly, indeed, 

 as to give to them a hazy appearance. I perfectly 

 satisfied myself that the peculiar humming proceeded 

 from the seated Syrphiis, and that the closed wings 

 were rapidly vibrating. I could not have been quite 

 certain of the species before the insect took flight, 

 since I can find in m\- diary of August no note of the 

 circumstance, and had, no doubt, hoped to repeat the 

 experience, and identify the species before noting. — 

 Charles Rohson, lullingworth, Ncwcastlc-oii-Tyne. 



Photographing Large Insects by Artificial 

 Light. — On the top of a tripod or camera stand may be 

 fixed a double board, hinged so that it will turn up at 

 right angles with its base as in theaccompanying sketch, 

 and supported by a side rod or slotted bar. It will be 

 seen that if the camera is screwed to the upright 

 board, the lens will point downwards to the ground. 

 It is obvious that if anything is placed on the floor, by- 

 using the camera in this position the object can be 

 very readily seen on the ground glass of the instrument. 

 Books, manuscripts and such like things that are diffi- 

 cult to fix up, can thus be ver\- easily copied, and wdth 

 a great saving of time. The size does not matter. 

 One has onl\' to lengthen or reduce the distance 

 between the object and the lens to get the necessaiy 

 reduction; but it is not for this purpose that I now 

 describe an arrangement I have successfully used for 

 some years in photographing insects, such as butter- 

 flies, beetles, or shells, leaves, single flowers, etc. 

 Much time can be saved, as one has only to place the 



object on some suitable support, and photograph. 

 Some people may int|uire aljout the shadow, as it 

 often mars the beauty of the photograph, though some- 

 times it adds very materially to its relief. To obviate 

 this, I place my object on a sheet of clear glass with a 

 piece of white or coloured paper, as the subject may 

 rec^uire, at such a distance as to cast no visible shadow. 

 That is to .sa)', the shadow is lost before it reaches the 

 paper. By this means one gets a negative of the 

 object only. Some subjects look better on a clear 

 ground, then use a sheet of white paper. For tinted 

 ground, a grey ; and for a black ground, a dull choco- 

 late paper will be found the best, as it seems to have 

 the least reflection and absorbs the light better than 

 black. .Such butterflies as the common- and marble- 

 whites, small blues, etc. , look better on a dark ground, 

 whereas nearly all the others show better on a clear 

 ground. The same remarks will apply to other 

 insects. In making a series of photographs of butter- 

 flies, the)' should all bear the same relative proportion 

 to one another, as in nature, and not be the same 

 size. To obtain this, they should be taken with the 



The "Freshwater Caisiera" for Insects. 



same extension of the camera, and the same distance 

 between the object and the lens. By working on these 

 lines, one can obtain a set of photographs that are 

 perfectly accurate in size, with relation to one another. 

 I have not said anything about the method of expo- 

 sure. This is the crux. If one's subject is not properly 

 lighted and exposed we do not get a negative worth 

 printing. I would at once say that if one has the 

 opportunity, there is nothing like daylight ; but it is 

 not every one who can spare the time to work in the 

 light of day. Further, many days during the winter 

 months are not fit for such work, so it is best to use 

 magnesium ribbon, as its photographic value is nearer 

 to daylight than anything else. With seven inches 

 of the ribbon, and a rapid, thickly-coated plate, one 

 will find it easy to get a good negative, full of detail, 

 and gradation of light and shade. The best developer 

 to use is pyro-soda. For the formulae, see any of the 

 photographic textbooks. I need scarcely remark that 

 any printing paper may be used, preferably those of 

 the gelatino-chloride type, as they give a brighter 

 image.— r.^e. Freshwater, F.R.M.S., 3, Fleet Street, 

 London, E. C, 



