As a demonstration model the system worked, but in order to repeat the process the whole apparatus had to be dismantled and reassembled. Papin quickly saw that to make an automatic cycle the steam would have to be generated separately in a boiler; however, he did not take the project further. Papin also designed a paddle boat driven by a jet playing on a mill-wheel in a combination of Taqi al Din and Savery's conceptions and he is also credited with a number of significant devices such as the safety valve. Papin's years of research into the problems of harnessing steam was to play a key part in the development of the first successful industrial engines that soon followed his death. The first steam engine to be applied industrially was the "fire-engine" or "Miner's Friend", designed by Thomas Savery in 1698. This was a pistonless steam pump, similar to the one developed by Worcester. Savery made two key contributions that greatly improved the practicality of the design. First, in order to allow the water supply to be placed below the engine, he used condensed steam to produce a partial vacuum in the pumping reservoir (the barrel in Worcester's example), and using that to pull the water upward. Secondly, in order to rapidly cool the steam to produce the vacuum, he ran cold water over the reservoir. Operation required several valves; when the reservoir was empty at the start of a cycle a valve was opened to admit steam. The valve was closed to seal the reservoir and the cooling water valve turned on to condense the steam and create a partial vacuum. A supply valve was opened, pulling water upward into the reservoir, and the typical engine could pull water up to 20 feet. This was closed and the steam valve reopened, building pressure over the water and pumping it upward, as in the Worcester design. The cycle essentially doubled the distance that water could be pumped for any given pressure of steam, and production examples raised water about 40 feet. Savery's engine solved a problem that had only recently become a serious one; raising water out of the mines in southern England as they reached greater depths. Savery's engine was somewhat less efficient than Newcomen's, but this was compensated for by the fact that the separate pump used by the Newcomen engine was inefficient, giving the two engines roughly the same efficiency of 6 million foot pounds per bushel of coal (less than 1%). Nor was the Savery engine very safe because part of its cycle required steam under pressure supplied by a boiler, and given the technology of the period the pressure vessel could not be made strong enough and so was prone to explosion.