Abstract: A detonating device principally intended for detonating an explosive charge in a well or borehole, and of the type which is actuated by pulling upwardly on a non-electrical line also used to lower the device into position. The device includes self-contained time-delay circuitry which requires a sustained mechanical actuating pull on the line for some predetermined time before an attempt is made to detonate the explosive. The circuitry includes a command switch actuated by pulling on the line, and a safety switch which must be closed before the command switch is closed, either manually or by hydrostatic pressure in the borehole. The circuitry locks in a safe condition if the command switch is closed first, or if one attempt has been made to fire the explosive, whether successful or not, thus allowing removal or repositioning of the device with complete safety.