HOGG. — FRICTION IN GASES AT LOW PRESSURES. 17 



ten per cent. This would indicate an absolute error of less than 

 0.000,001 mm. 



The investigation is now being extended to the case of oxygen and 

 nitrogen. The data obtained by using these gases, besides showing 

 whether their behavior is like that of hydrogen, should give some more 

 information regarding the quantity, /?, which enters the foregoing 

 discussion. 



Jefferson Physical Laboratory, 

 Cambridge, Mass. 



vol. XLV. 



