Abstract: An ultrasonic testing device for inspecting thermit rail welds in a track is disclosed. The device may be passed over the top of a rail weld in a track to indicate whether there are any faults in the weld. The device includes a longitudinal shoe which may be placed lengthwise along the top surface of the rail, a transmitter which transmits an ultrasonic energy pulse and a receiver for receiving the ultrasonic energy pulse, the transmitter and receiver being positioned and aimed so that an energy pulse is directed downwards towards a location on the under surface of the rail and reflects upwards as an echo pulse so that it is received by the receiver. The indication of the transmittal and receival of the pulse is shown on a cathode ray tube or multi-channel pen recorder. A method of inspecting the thermit rail weld is also disclosed. This includes the transmission of a pulse at an angle of at least 45.degree.