Concrete test cylinders cut from diamond drill cores through completed tunnel lining, Detroit water supply system
Description:
View of concrete test cylinders cut from diamond drill cores through completed tunnel lining, Detroit water supply system. Printed on front: "#33. Springwells tunnel contract section no. 4. Mark R. Hanna Co., contractor. View showng typical compression test failures of standard 6" x 12" concrete test cylinders cut from diamond drill cores taken through completed tunnel lining. Left to right: cylinder nos. 228-228A-229 top and bottom 231A-231. Oct. 22, 1928."
