ON A NEW MRTITOD OP CALIBRATING, &C. 341 



upoii tlie pressure at wliich tlie gas is suppliée! to the burner. lu the 



Fig. 1. 



(irst, we liave two separate C3'liiidncal jets of sniall size (Fig. la) wliicli^ 

 witli iucreasiiig gas ])ressure meet without uuitiug; each beiug deflected, 

 by ini])ingiiig iipou the other, iuto 

 a vertieal plane (Fig. 1/.»). At still 

 liiglier pressures the actual uuiou 

 of the two jets takes place^ giving 

 the tlame the structure showu iu 

 (Fig. le), m whicli the two cj'liu- 

 drical jets of gas iu the process of 

 combustion uuite to fonu a single 

 flat vein or envelope which con- 

 stitutes the luminous portion of 

 the tlauie. Whcn this third stage 

 is reaclied, tiiere is great stability 

 of fonu and ])osition. Siudi atlante 

 responds with a sharp latéral mo- 

 tion to air waves sucli as are pro- 

 duced by the slaraming of a door, 

 but is comparativelj unaffectedby 

 slight drafts. Even in a room not 

 essentially free from air currents 

 the latéral motions of tlie tlame, 

 which may be accurately observed 

 by throwing an enlarged image of 

 it, viewed edgewise, upon a screen, 



rarely amount to more than .1 nnu. ^ 7Ji m. ^ /?i ?n . q ?n m 



and in an especially protected Fif. 2. 



