CHAS. LENTZ & SONS 
The inner glass door in the larger incubators is of bevelled plate. The 
outer doors are prismatic, and are properly and accurately fitted and mitred, with 
felt buffers to ensure perfect fit and close contact. This is of the utmost import- 
ance, especially in the large incubators for tuberculin or diphtheria antitoxin 
manufacture. There is no sliding cover to the outer door, as this increases the 
cost, and has not a single advantage to the practical bacteriologist. A ventilator 
is supplied at top of incubator to allow of the escape of burned air and gas. In 
incubators where this is omitted there is danger of explosion, and there is much 
fluctuation of temperature. The large tubulatures provide plenty of room for 
large gas regulators, such as the Dunham, etc. They are all provided with water 
level and stopcock and movable shelves. 
The visible copper walls are highly polished, also the copper edges and frame- 
work, which are also lacquered. These incubators are now in use in many of the 
largest and best-equipped laboratories in the United States, and have invariably 
52 
