The steam jacket that surrounds the cylinders did away with the need for a separate dome ( the patent stated that the cylinders were placed within the dome ).
12.
A fundamental change in working principles was brought about by steam engine, which incorporated a series of radical improvements, notably the closing off of the upper part of the cylinder, thereby making the low-pressure steam drive the top of the piston instead of the atmosphere, use of a steam jacket and the celebrated separate steam condenser chamber.
13.
Watt's critical insight, arrived at in May 1765, was to cause the steam to condense in a separate chamber apart from the piston, and to maintain the temperature of the cylinder at the same temperature as the injected steam by surrounding it with a " steam jacket . " Thus very little energy was absorbed by the cylinder on each cycle, making more available to perform useful work.
