July 28, 192 1] 



NATURE 



697 



in policy and encourage interchange of students. 

 More important still as an actual need of the day 

 seems to be this :' that universities which associate 

 themselves with technological institutions of originally 

 independent growth shal' bring the studies, teachers, 

 and students effectively into the precincts and life of 

 the university. Equally important does it seem that 

 this should be done so far, and only so far, as these 

 studies, teachers, and students can be rightly regarded 

 as conforming to the standards of a university. It is 

 to be feared that there lie here practical problems of 

 grave difficulty, and that we may be entering upon a 

 troubled time. The difficulties for the universities lie 

 mainly in the suspicion, which they so easily incur, of 

 possessing all those failings that are apt to beset aristo- 

 cracies, and when they are prescribing restrictions in 

 the light of experience and with a disinterested desire 

 for the common good, thev may easily enough be 

 regarded as acting merely in a disdainful spirit of 

 exclusiveness. Another danger, of course, lies in an 

 eager spirit of accommodation, a disposition to please 

 the multitude, and a love of peace, amid which essen- 

 tials may be sacrificed to gain the mere semblance of 

 success. 



In the restlessness of our present world it is diflficult 

 to gauge the currents of opinion that will mould or 



remould the institutions of our country. But so far 

 as education is concerned it seems clear that, if we 

 are to accept their spokesmen, the rank and file of 

 the teeming world of labour have set their heart in 

 something like clear purpose to the ends that shall 

 be sought. They will not have it that their new and 

 increased education shall be permeated and dominated 

 by a sordid or material aim. They begin to suspect 

 the agencies that make their chief promise a cleverer 

 performance of the daily task or the earning of a 

 larger wage. In their revulsion from such an object 

 they threaten to repudiate what in truth in its proper 

 place, among other things, will lighten and enlighten 

 their labours. 



There is no sign of the times that to me seems 

 more hopeful, for I see in it the promise of an end 

 to the far-reaching and incalculable mischief that has 

 come of a false distinction between useful and useless 

 knowledge. But there are opposing forces to contend 

 with. 



It seems to me that there is no service of universi- 

 ties more needed now than to exhibit in the centres 

 of highest education, which can so easily lead the 

 way, the true intellectual nurture of industrial life — 

 the embodiment of technology in full and fruitful 

 fellowship and interplay with accepted liberal studies. 



New Apparatus for Showing the Tracks of a-, p-, and X-rays. 



IT will be remembered that Mr. C. T. R. Wilson 

 described his original cloud expansion apparatus 

 as used for showing the tracks of o- and /3-rays and 

 of X-rays before the Royal Society in April, 191 1, and 

 at that time the Cambridge Scientific Instrument Co., 

 Ltd. (now the Cambridge and Paul Instrument Co., 

 Ltd.), took up the manufacture of this apparatus. The 

 manufacture of apparatus of this class was, however, 

 entirely stopped by the war. 



Lately Mr. Takeo Shimizu, of Japan, 

 working at the Cavendish Laboratory, 

 Cambridge, has considerably modified 

 Mr. Wilson's original apparatus, and 

 the Cambridge and Paul Instrument 

 Co., Ltd., is now putting the im- 

 proved design upon the market. In 

 Mr. W'ilson's original apparatus only 

 a single expansion was obtained. It 

 was thought to be necessary to give 

 a comparatively rapid expansion in the 

 working chamber, and this was ob- 

 tained by connecting the space under 

 the moving piston to another space 

 which was previously evacuated. The 

 moving piston was, in consequence, 

 suddenly sucked down against a 

 rubber stop. Mr. Shimizu has found 

 that the sudden expansion is not 

 necessary, and has, therefore, ar- 

 ranged for .a reciprocating piston, 

 and he obtains cloud tracks of the 

 rays at each expansion, which may b^ 

 timed to occur at rates from about 50 

 to 200 per minute. The instrument 

 thus designed is extremely simple, but there are 

 several important points to' which attention must be 

 given for successful operation. 



The apparatus is shown in Fig", i. The crank (not 

 seen in the illustration), which is driven either from 

 the hand-wheel B or by means of a small motor, 

 drives an uprigfht connecting rod, which in turn 

 drives a horizontal connecting rod D. The far end 



NO. 2700, VOL. 107] 



of D slides in a sleeve E, which is free to rock in the 

 piece F. The piece F can be adjusted in a horizontal 

 direction by means of the screw G. The piston-rod 

 H is connected near th^ middle of this latter con- 

 necting-rod. Since the crank is of constant length, the 

 horizontal adjustment of the piece F alters the length 

 of the stroke given to the piston-rod H. By this means 

 the expansion ratio at each stroke in the working 



Fig. I. — Shimizu expansion apparatus. 



chamber K can be adjusted while the instrument is in 

 operation. 



In order to obtain a good picture of the rays which 

 become visible at each expansion by the formation 

 of linear clouds on the ionised particles in the ray 

 tracks, it is necessary that these clouds be dissipated 

 during the compression stroke. This is done bv form- 

 ing- a vertical electrostatic field in the expansion 



