The following thesis embodies a limited literary perusal of the subject and the results of an investigation into the reliability and adaptability of a portable hardness testing device, to commercial testing. The device, a product of the Sheffield works of Brown-Bailey Co., is the property of the Canadian National Railways. The formula supplied with the instrument had been lost, and Mr. J. Gilchrist, Chief Inspector of Materials for the Mechanical Department of C.N.R. (Western Region), left the device and a standard bar with Mr. J.F. Cunningham at the Engineering Laboratories. The evolution of a suitable formula or curve to replace the one lost was considered as a possible motive for a graduation thesis. Securing the recommendation of Assist. Prof. W.F. Riddell, and the approval of the Civil Engineering Department, the investigation of the device was begun on January 28, 1931. Three series of tests were made on the device and a curve was obtained that proved to be both simple to use and as accurate as is consistent in commercial testing of hardness. All of the apparatus, except the microscope lamp loaned by the Geology Department, and all of the materials used in the testing, except two standard bars obtained from Mr. J. Gilchrist, was obtained from the Engineering Laboratories. The testing was done entirely in the Engineering Laboratories, being completed on April 10, 1931.