50 Tue Microscope. 
A cheap injecting apparatus can be made according to the 
illustration as follows: 
A, represents a pail partly filled with water, which can be 
raised or lowered, to regulate the pressure, by fastening one end 
of a cord to the handle of the pail and then passing the other 
end over a pulley fastened to the ceiling of the room; 4, is a 
