F. Waldo—Filling of Barometer tubes. 19 
mercury fall. The tube f is then sealed or a stop cock in it 
turned, cutting off the Sprengel pump; the Bunsen burner 
under c¢ is lighted, and the mercury will distill over into the 
barometer tube, which will thus be filled without allowing the 
mercury to come into direct contact with the air. 
The barometer tube should be constantly watched in order 
to detect any air bubbles that may be carried over; when seen 
ey must be cooked out by heating the tube slightly by means 
a Bunsen burner. When the barometer tube has ‘become 
rth! with the mercury, the cock at x can be ¢ closed, the sealing 
wax broken and the tube replaced by ano >the 
This method is similar to the one employed by Wig 
St. Petersburg, only he uses the Weinhold apparatus. 
Hamburg, June, 1883. 
