The following article, first in a series of five on the activities of the Engineering School, was written for the CRIMSON by Howard H. Alken, instructor in Physics and Communication Engineering.

The Department of Sanitary Engineering, under the leadership of Professor Gordon M. Fair, is at present concerned with a variety of important problems.

The spread of infection caused by micro-organisms in the air, particularly bacteria and living virus, may be combated by the use of ultra-violet light barriers which destroy the organisms.

The pollution discharged in rivers by the drainage systems of cities and industrial wastes is destroyed largely by oxidation, and the oxygen requirements of such rivers is therefore a matter of great importance.

The increasing number of automobile trailers presents the problem of safe disposal of human wastes from such trailors in order to prevent the spread of possible infection.

These problems, together with the problem of stabilization of organic matter in municipal sewage treatment works, are representative of the researches in progress at the present time.

The quantiative measurement of smells and odors was long considered a difficult problem in applied science until Professor Gordon M. Fair and Mr. William F. Wells developed their osmoscope.

This instrument enables an observer to dilute odorous gases with clean air until the odor is no longer detectable, and thus relative amounts of odorous gas and air serve as a measure of the intensity of the odor.

Although this device was not described in scientific literature until late in 1934 it has already found numerous applications in industry. One of these is the study of odors in Pullman cars equipped with recirculated conditioned air apparatus. The use of the osmoscope enabled the engineers of the Pullman Company to measure the odors present and so design suitable methods for their removal.

The osmoscope and its immediate applications to industrial problems are indicative of the highly practical research carried on in the Sanitary Engineering Department of the Graduate School of Engineering.

This department is concerned directly with the problems of State and Municipal sanitation, such as water supply and waste disposal, and in cooperation with the Harvard School of Public Health also considers the problems arising in industrial sanitation, particularly with sanitary air control.

Like most fields of investigation in modern engineering research. Sanitaray Engineering makes application of the detailed knowledge of a great many different fields, such as Civil Engineering, Biology, Chemistry, Bacteriology, etc.

At the present time the Department of Sanitary Engineering has 37 graduate students working for advanced degrees, 35 of whom are specializing in State and Municipal Sanitation, and 3 in Industrial Sanitation.

Of these, 23 are on leave of absence from the Public Health Departments of various states and foreign countries, including Mexico, Poland, and Turkey, and 2 Professors on leave of absence from other universities.

In the field of water purification, the Department of Sanitary Engineering has intensively studied the hydraulics of sand filteration and means of cleaning such sand filters to maintain their efficiency. The osmoscope has also been used in studying the odors and tastes in drinking water, and further studies have been made in the control of microscopic organisms.

The heat and energy relation in the destruction of sewage matters has also been investigated; previous research has shown that the combustible gases evolved in the process of destruction may be burned as fuel to increase the temperature of the digesting organic material, and thereby hasten the digestion by stimulating the life activities of the organisms of decay.

This whole problem has been carefully investigated and optimum conditions of plant operation determined, thereby making for greater economy.

In cooperation with the School of Public Health the Sanitary Engineering Department has carried out numerous researches in the study of air-borne infection. These investigations have considered the infective range of droplets expelled from the nose and mouth, and engineering means for preventing the spread of infection.

Numerous means have been utilized for destroying the micro-organisms responsible for such infection, but of these, treatment of the air with ultraviolet light seems at present to be the most promising