CERTAIN ASPECTS OF HIGH-PRESSURE RESEARCH 



By Prof. P. W. Bridgmax, Ph. D. 

 Harvard University 



As some of you know, I have been occupied for a number of years 

 in determining the effects of high hydrostatic pressure on a number 

 of physical properties. To-day, I propose to stop for a minute for 

 a general stock taking, to outline briefly some of the results obtained 

 and to suggest partially their possible significance. I am impelled 

 to do this because the variet}^ of subjects touched by this high- 

 pressure research is so great, and the character of the information 

 obtained in many cases so special, that the whole effort is likely to 

 appear without general scheme or significance. But I believe that 

 different limited aspects of the subject will be of interest to different 

 individuals; by presenting to you the general outline, I hope to 

 make it possible for any individual to become aware of those aspects 

 of the work which may be of special significance to him. 



My general attitude in my investigation has been that high pres- 

 sures are a tool which may be significantly applied to the discussion 

 of many different problems. It is not usual, however, for an experi- 

 menter to devote himself to exploiting a single tool of research. I 

 am somewhat in the position of a small boy with a new jackknife 

 who rushes about trying it on every conceivable object. Doubtless 

 the more mature method is to maintain a tool box from which one 

 might take the jackknife wdien one has to sharpen a pencil, or an 

 augur when one has to bore a hole. I may suggest, in partial extenu- 

 ation of my attitude, that there seem to be very few jackknives in 

 the world, or at least very few people who seem willing to use them, 

 and there really does seem to be a certain amount of whittling that 

 needs to be done. 



The kind of problem which can be attacked most successfully by 

 the use of high pressures is not that which is now most interesting 

 to most physicists, nor which appears to be most fundamental. 

 This tool is not particularly adapted to probing questions of the 

 constitution of the atom and particularly of the nucleus, but is better 



1 Address delivered Tliursday, Sei)t. 18, 1924, on the occasion of tlie celebration of the 

 centenary of the founding of Tlie I'rniil;lin lustiluto. Reprinted by permission from the 

 Journal of The Franklin Institute, I'hiladelphia, August, 1925. 



157 



