234 MEMORIES OF MY LIFE
and is now under the Directorship of Dr. W. N. Shaw, with a large governing body, whose meetings are much less frequent than those of the Council had been, and interfere less in details.
My long connection with the able men with whom I co-operated for nearly forty years on the Meteorological Committee and Council has given very great pleasure to me, and I had the satisfaction in its earlier days, when new instruments and methods were frequently called for, of being able to do my full share of the work. I will mention only one or two things about which I was much occupied, as examples. Part of our action was to maintain a few wellequipped self-recording Observatories-that is to say, where the instruments wrote down their own movements, photographically or otherwise. For instance, a sheet of photographic paper was moved slowly by clock-work in front of a barometer. The barometer stood in front of a slit in a screen, with a lamp on the other side. The light of the lamp passed freely through the empty portion of the glass tube on to the sensitive paper, but was shut off by the mercury. Hour lines were automatically marked upon. thee paper. The result was technically called a photographic " tracing," which showed at each moment of time how the barometer then stood. An analogous contrivance was' adapted to every one of the other instruments.
All the instrumental data were recorded by these tracings, but they were much too cumbrous in form and size for easy comparison. The question then arose whether it would not be possible to reduce these voluminous documents and print them in a