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 Meteoro- 

 logical 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 well- 

 equipped self-recording Observatories that is to say, 

 where the instruments wrote down their own move- 

 ments, 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 the 

 paper. The result was technically called a photo- 

 graphic " 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 



