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May 18, 1883. | THE PHOTOGRAPHIC NEWS. 317 SUNSHINE AND THE BAROMETER. BY CAPTAIN ABNBY, K.E., F.E.S.* It is specially interesting to landscape photographers to get an insight into the probable kind, of light they may encounter when ; in the field ; and although forecasting is uncertain, yet there is always a balance in favour of it, if the proper causes are taken into consideration. There seems to be a great argument in 1 favour of the fact that the probable amount of sunshine varies with the height of the barometer, and this has long been recognised by the manner in which our so-called weather-glasses ' are marked. At 30'5 in. they read, set fair ; at 30 in., fair ; at 1 29'5, change ; at 29 in., rain ; and at 28’5 in., much rain. It may be almost predicated that the more free from cloud (i.e., the more sunshine there is) the fairer the weather appears, and so we may look upon the weather-glass indications as 30’5 in. sky clear, 30 in. few clouds, 29 in. average number of clouds, 29’0 cloudy, 28’5 very cloudy. This is as Mr. Whipple classifies them in a communication to the Meteorological Society in 18793 In it he dismisses the effect of the height of the barometer on the amount of sunshine, and comes to a conclusion which for Kew in the years 1877, 1878, shows that readings of the barometer as regards amount of sunshine are most misleading. In the following diagram the strong curue will show the average amount of sunshine with the barometer at different heights; that is, the total amount of sunshine which was noted, compared with the total amount possible. The chain dotted curve shows the amount of cloud noted at Kew, and the one is almost directly comparable with the other. It must be recollected that the cloud measures are taken by the compu tation of an observer, while the sunshine-records are written by the sun itself. It will thus be seen that at Kew for those two years the maximum sunshine appears when the barometer has a height of about 30'15 in., and that when higher the cloud-mist returned, till at 30'6 in. the sun shone no more than when the mercury stood at 29-2 in. In London and neighbourhood, if this record is any guide, the weather may be expected to be most favourable for landscape work when the barometer is at about 30 in., as then there should be a proper proportion of cloud and sunshine to give those effects of light and shade which photography can render so well. When the sky is perfectly cloudless, a photograph is not' so rich in gradation as when there are white fleecy clouds about, which act as reflectors to light up the cloud-shadows. Now this is the effect at Kew, which in Mr. Whipple’s remarks will not necessarily apply to other places, for un doubtedly the merest change in direction at about 80:3 in - is in a measure to be attributed to the haze and cloud which at Kew accompany the east wind so frequently prevalent during periods of high barometer pressure or acute cyclones. It would be well that the series of observations now taken in other parts of the c untry should be tabulated in the above way, in order to see at what height of the barometer the return of cloud may generally be expected. One thing is quite evident— that the beautiful symmetry of the marking of the supposed weather at over } in. on the • The Photographic Journal. barometer is fallacious for above 30'5 in., supposing the sun was always shining when it was above that height. RECOVERING SILVER FROM WASTE GELATINE EMULSION PLATES OR PAPER. BY J. PIKE.* The subject matter of this paper was written some months ago, but publication was deferred because I had at the time some thought of turning my idea to business account. From one cause or another—pressure of other matters and so on—nothing was done in this way. About three weeks ago, however, I noticed in one of the photographic journals a statement to the effect that a German chemist practised a certain method so nearly akin to my own that I decided to bring the subject before this Association in the form of a short paper, and at as early a date as possible. I found myself some six or eight months ago, after a variety of experiments with gelatine emulsion making, with some accu mulations of waste. Even the most experienced manufacturer of gelatine dry plates must have occasionally a bad lot, and the question is forced upon one—What is to be done with it ? And not only waste emulsions, but waste plates. Now, I do not wish anyone to suppose I was guilty of such an absurdity as to coat plates with an emulsion I knew to be bad. Such was not the case. The fact is, my drying cupboard was faulty, and I had occasionally batches of plates altogether unreliable from the fact that desiccation proceeded so unevenly as to make the plates practically useless. I suppose in the ordinary way these would be cleaned off and the silver bromide allowed to run down the • Read before the Nesscastle-on-Tyne and Northern Counties’ Photo graphic Association.