the use of the same stereopticon for both rooms. The stand could easily be made to revolve and if the rooms are not used simultaneously there should be no difficulty. A separate room of this kind is necessary where motion pictures are to be shown and a fully equipped lecture room should not be without it.
The development of the nitrogen lamp has recently quite revolutionized stereopticon systems. A 1000 or 1500-watt lamp attached to an ordinary circuit can be operated noiselessly by even the most unskilled person with satisfactory results. Too much power is not wanted with slides and a cheap machine with good lenses provided with one of these lamps is perfectly satisfactory in a small room. In choosing a stereopticon it is well to remember that if it is possible to load and unload the slide carriage from the side next the operator much fatigue is spared. Constant reaching over to the opposite side of the machine to remove or put in a slide is tiresome as well as slower.
The ventilation of the lecture room should be carefully considered. In case it is impossible to instal the special lecture room system with the outlets under the seats there should always be outside windows which can be opened in case of need. It is unwise to put the lecture room on the
