430 



SCIENCE. 



[N. S. Vol. VII. No. 169. 



expression for the differential of the energy lost 

 in an element of time. The general form for 

 the energy lost is : 



U^ j¥siu Tp (Oi +« 



>J? 



in which f is the 'angle of repose,' M is the 

 driving moment, osi and o« are the angular 

 velocities of the driving and driven wheels re- 

 spectively, r is the distance from the point of 

 contact to the pitch point, and I is the perpen- 

 dicular upon the resultant line of action from 

 the axis of the driver. This integration was 

 effected for the 'approach,' then for the 're- 

 cess,' and their sum was divided by the whole 

 energy exerted by the driver. This gave the 

 ratio of energy lost to energy exerted. 



For epicycloidal teeth the exact formula was 

 very complex, but a close approximation was 

 obtained in the following form : 



Eatio = j-o 'J-i^VO.546/ -}- 2.72 '^/ 2 j . 



For involute teeth an approximate formula 

 was also obtained in this form : 



Eatio = 



+ '"'(/cot9 %f^co\?B) 



2r. 



in which S is the constant angle between the 

 normal to the teeth and the line of centers. 

 These ratios subtracted from unity give the 

 efSciency. 



For the sake of comparison, a table was pro- 

 duced giving the efficiency for different values 

 of the coefficient of friction /, and for equal 

 wheels and for the same number of teeth, 12, 

 on each wheel. 



Efficiency of Spur Wheels. Equal wheels 

 with 12 teeth each. 



Dr. Amand Ravold demonstrated the method, 

 recently introduced by His, of differentiating 

 the typhoid bacillus from Bacillus coli-com- 

 munis, by the use of semi-solid acidulated 

 media, in which, at blood temperature, the 

 round colonies of the typhoid bacillus assume 

 a peculiar iimbriated form of growth, because 



For Plate Cultures. 



Agar 10 grams. 



Gelatine 25 " 



Beef extract. . .5 " 



Glucose 10 " 



Salt 5 " 



Normal acid.. .20 ce. 



of the motility of the bacteria in the slightly 

 yielding medium, which, in most cases, readily 

 distinguishes them from the more whetstone- 

 shaped colonies of the colon bacillus, which 

 does not produce the peculiar fimbriation in 

 plate cultures. In tube cultures in the same 

 general medium, but prepared with a slighter 

 acidity and somewhat less solidity, a uniform 

 clouding of the entire tube, due to the swarm- 

 ing of the bacteria, was shown to be character- 

 istic of the typhoid bacillus, while the colon 

 bacillus was definitely confined to the imme- 

 diate vicinity of the thrust. The media in 

 both cases are made up without peptone. The 

 formulse are : 



For Tube Culture". 



Agar 5 grama. 



Gelatine SO '■ 



Beef extract. . . 5 " 



Glucose 10 " 



Salt f< " 



_ __ Normal acid. ..15 cc. 



Tbe wbole increased to 1000 The wliole increased to 1000- 

 oe. - cc. 



The growth of the two species in question, on 

 potato and in milk cultures with litmus, was also 

 demonstrated. 



Eight persons were elected to active member- 

 ship. 



William Trelease, 

 Recording Secretary. 



TOREEY BOTANICAL CLUB, FEBRUARY 23, 1898. 



This meeting was held in the large lecture 

 hall of the College of Pharmacy, and about 150 

 persons were present. Vice-President Rusby 

 presided. The minutes were read' and ap- 

 proved. Arrangements were announced for 

 summer courses in botany, provided by the com- 

 mittee of instruction of the Club. Course 1, is 

 to commence March 4th, at the College of Phar- 

 macy under Mr. W. A. Bastedo, with weekly 

 lectures and excursions on Saturdays. Pursu- 

 ant to motion of Dr. Britton, the chairman made 

 this evening the announcement of the Field 

 Committee for the year 1898, to consist of three 

 members, with power to add to their number. 

 The Committee was announced to consist of Mr. 

 W. M. Clute, chairman ; Professor F. E. Lloyd 

 and Mr. W. A. Bastedo. The evening was de- 

 voted to an illustrated lecture by Mr. Cornelius 

 Van Brunt on the wild flowers of the Canadian 

 Rockies, with lantern slides exquisitelj' colored 

 from nature by Mrs. Van Brunt. Numerous- 



