CATALOG 1952-1953 CL. 450.-Highway Construction and Materials. 2 hours, and 3 hours field and laboratory practice, 3 credits. Prerequisite: CL. 321. Offered 2. Construction surveys; preparation of final estimate; earthwork equipment and operations; subgrade and base design and construction, including soil stabilization methods; bituminous paving mixtures. GRADUATE COURSES CL. 521.-Advanced Metal Structures. Variable credit. Prerequisites: CL 438, CL. 335. Corequisite: CL. 538. Offered 2. Studies of structural stability; application and economics of available metals; prob- lems in structural details, fatigue of structural members; evolution of specifications; types of movable bridges; RR bridge specifications; the design of steel rigid frames. CL. 523.-Advanced Concrete Structures. Variable credit. Prerequisites: CL. 438, CL. 333. Corequisite: CL. 538. Offered 1, 2, 3. Comparisons of modern methods of concrete proportioning; design with relation to ultimate; prestressing; plastic flow; special structures; admixtures and protective treatments; study of research development; the design of concrete rigid frame bridges. CL. 526.-Three Dimensional Stress Analysis. 3 hours. 3 credits. Prerequi- site: CL. 438. Offered 1, 3. The resolution of forces, computation of reactions, and calculation of forces and stresses in structures that cannot be reduced to co-planer structures. CL. 527.-Advanced Sanitary Engineering. 3 hours or its equivalent. 3 credits. Prerequisites: CL. 426, CL. 429. Offered 1. An advanced study of the biological, chemical and physical principles utilized in water, sewage, and industrial waste treatment processes. CL. 528.-Advanced Sanitary Engineering. 3 hours or its equivalent. 3 credits. Second half of the course CL. 527-528. Offered 2. CL. 529.-Advanced Sanitary Engineering Design. 3 hours or its equiva- lent. 3 credits. Prerequisites: CL. 333, CL. 429. Offered 1, 3. Special problems in the design of water, sewage, and industrial waste plants. CL. 530.-Problems in Sanitation. 3 hours or its equivalent. 3 credits. Prerequisites: CL. 426, CL. 429 and permission of instructor. Offered 2. Approved problems for study or research selected from any field of sanitary specialization. CL. 538.-Analysis of Statically Indeterminate Structures. 3 to 6 credits. Prerequisite: CL. 438. Offered 1, 2, 3. Frames with variable moment of inertia; closed rings; column analogy; secondary stresses; continuous trusses; columns; design problems. CL. 540.-Bio-statistics. 3 hours. 3 credits. Prerequisites: CL. 422, MS. 354. Offered 2. Principles of statistics as applied to populations, epidemiology, morbidity and mor- tality rates. The statement "Offered 1" means offered first semester; 2, second semester; 3, summer session.