This thesis was prepared as a result of the growing interest in and the increasing importance of electric welding as applied to many types of manufactured products. Although the art of electric welding is comparatively new, great steps have been taken in its adaptation to industry. As yet the process is underdeveloped, and no information is available whereby one may know with certainty the behavior to expect from a welded joint. The composition of the metal to be welded, the composition of the welding rod, and the method used in welding are but a few of the factors which determine the ultimate strength and behavior of an electrically welded specimen. Far from claiming the credit for a comprehensive report on electric welding, the authors of this thesis admit that it of necessity is limited in its treatment of the subject. Both steel and wrought iron specimens were tested, the steel specimens ranging from 0.2 to 0.5 per cent carbon content. At first the investigation embraced lap-welded and butt-welded joints, but because of the fact that properly made lap-welds never break in the weld, and hence give no indication as to the strength of the weld, this type was abandoned, and all V-type butt-welds were used. All of the welds, with a few exceptions which will be mentioned later, were tested in tension, their tensile strength being used as an indication of their ultimate strength. The Tinius Olsen strain gage was used in obtaining the elongations of the specimens. In the tables which follow, the values in the deformation column will be expressed in Tinius Olsen units, each unit being 0.0003333 of an inch. If the value in the deformation column were 2.3 and this value were desired in inches, the conversion factor 0.0003333 should be multiplied by 2.3, giving 0.00076659 inches as a result. The welding was done with a Lincoln Stable Arc Welder. During the welding operations the voltage was kept at 60 and the amperage was about 150. / M.S.