"Should any of my readers have failed to get useful cloud negatives, and are close upon giving up in despair, as I have known many to be, I would recommend them to forthwith take a slow plate, insert F 45 stop in the lens, and make a quick shutter exposure on some wellmarked sun -lit clouds. Then develop with a slightly diluted developer, and see what comes of it. Probably, if the clouds be heavy, they will be a little under-exposed. Then, from this as a basis it should not be difficult to get on the right road."