164 
A. W. CLAYDEN-APPLICATION OF 
diminishes the whole brilliancy of illumination so greatly that 
there is comparatively little difficulty in judging the exposure. 
Indeed some of my best pictures represent clouds in such a position 
that the mirror should theoretically have been all but useless. 
Before I had the mirror I used to get good negatives now and 
then, but most of my attempts (at cirrus clouds) were failures. 
How, using the reflector, I seldom have a failure unless I have 
committed one of those errors common to all photographers, such 
as exposing one plate twice. 
The lantern-slides which I show this evening will enable a 
judgment to be formed as to how this method works. They will 
also indicate better than any number of words the great desirability 
of takiug a series of views of the same cloud, or a number of views 
of the same part of the sky, at stated intervals of time, so that the 
photographs may not only record cloud-forms, but also some of their 
changes and something of their motion. As to the merit of the 
method, it should be remembered that all the negatives I have 
taken were done under the great disadvantage of the murky 
atmosphere of a London suburb. Clear, then, as some of them are, it 
stands to reason that much better work should be possible in the 
pure air of a country district. 
Tor meteorological photography to he thoroughly successful, its 
devotees have to do some things which are not usually supposed to 
be wise. In the first place the dark slides should be kept charged 
with plates. This is apt to result in dust-specks and other 
photographic flaws; but a picture with one or two .technical 
defects is better than no picture at all, and clouds will not often 
wait while the apparatus is prepared. It must be ready for use. 
Tor a similar reason I always keep my cameras set up in correct 
focus for a distant object. It never pays to try and focus on a 
cloud. The margins of the objects are often so ill-defined that 
focussing is a very troublesome matter. Everything should be 
adjusted to suit some distant thing, such as a church, a house, 
or a tree. Again, to get clouds well into the field of view, the 
camera should be mounted in some way that will permit of free 
movement. A ball-and-socket joint under the tail-board would do, 
but for myself I prefer to have the camera to swing bodily between 
two uprights as a gun swings on its trunnions. This is a much 
more rigid mount than the ball-and-socket, and it can easily be 
rigged up by any one who can handle simple tools. 
There is one defect in the mirror-method which I ought to 
mention. This is that the image is reversed as regards right and 
left, but if the prints from it are transparencies on glass, this is, of 
course, got over. 
Clouds, then, are the phenomena to which we would invite 
special attention. But there are many other things which should 
be recorded. Tor instance, floods following an extraordinary rain¬ 
fall or sudden thaw, frozen rivers, remarkable hailstones, snow- 
crystals, and anything unusual produced by weather-changes. 
Even somewhat persistent objects, such as the glaciers of the 
