Abstract: A drop device, method and article of manufacture used in measuring lagtime in the drilling of a well. A unique container with calcium carbide is inserted upwardly by its guide end into the open end of a pin connection prior to its threaded assembly into a lower box connection on drill pipe. The container is handled by a resilient member during placement into the pin connection and secured in place by a loop on the resilient member. The container is formed in a right cone of thin sheet material and its tapered sides are waterproof, and a disc seals the bottom or floor of the cone. The container is held in the pin connection with the floor adjacent its lower end. The pin and box connections are assembled and resumed drilling fluid flow fragments and disperses the sheet material whereby the calcium carbide converts to acetylene that is readily detected in the outflowing drilling from the well.