68 
NATURE 
[| NovEMBER 19, 1903 
valves were all worked by hand, but automatic devices were 
soon introduced. The first appears to be that of actuating 
the injection-cock by means of a buoy in a pipe connected 
to the cylinder. Desaguliers thus describes the apparatus :— 
““ They used to work with a buoy in the cylinder enclosed 
in a pipe, which buoy rose when the steam was strong 
and opened the injection and made the stroke.’’ It is said 
that a boy, Humphrey Potter,’ added a catch or “‘ scoggan ”’ 
which the beam opened, and by this means the speed of | 
the engine was increased from 8 or to to 15 strokes per 
minute. 
Barney’s illustration of the Dudley Castle engine (erected 
in 1712) was made in 1719, and contains the plug-frame 
and tumbling-weight device attributed to the invention of 
Beighton in 1718. It is possible that the tumbling-weight 
had just been added for actuating the steam-valve. The 
injection-valve is released by the buoy said by Desaguliers 
to have been enclosed in a pipe attached to the cylinder, 
but here shown in a pipe attached to the boiler. The 
scoggan is also shown, and it is clear that the only thing 
that Humphrey Potter added, if he added anything, was a 
cord to cause the plug-frame to actuate the scoggan in- 
stead of the float doing it. 
Newcomen had associated with him Cawley, a plumber | 
and glazier, and it will be observed that the pipes of the 
engines were at first made of lead with plumber’s joints. 
In the early days the steam cylinders only were obtained | 
from iron-founders, and the other parts of the engine were 
built by local blacksmiths, carpenters, and plumbers, under | 
the direction of an engineer. 
The engine was first fixed on a boiler of haystack form, 
but the vibration of the engine so loosened the joints that 
it was found advisable to secure the cylinder to strong 
wooden beams above the boiler. At a later date the engine 
was fixed on a separate foundation by the side of the boiler, 
and as time went on iron pipes were substituted for lead, 
and the waggon-boiler was introduced to take the place | 
of the haystack.” 
Among the first erectors of the Newcomen engine were 
the Hornblowers, in Cornwall. Newcomen visited Mr. 
Potter, of Bromsgrove, and erected an engine near Dudley 
Castle in 1712. This is the historical engine in which 
injection in the cylinder was first used. In the vicinity 
lived Joseph Hornblower, an engineer who 
acquainted with Newcomen’s engine, and who was sent 
for into Cornwall about 1720 to 1725 to erect an atmo- 
‘spheric engine at Wheal Rose Mine, near Truro. 
It may be interesting here to observe, on the authority 
of Cyrus Redding, a greatgrandson of Joseph Hornblower, 
and author of ‘‘ Yesterday and To-day,’’ &c., that the 
Newcomen engine was not such a simple machine as only 
to require the attention of boys as stated 
histories, but that it required the united exertion of three 
men to start the engine. 
A second engine, it appears, was erected by Hornblower 
at Wheal Bury or Chasewater Mine. A third at Polgooth. 
Joseph Hornblower then left the county, and his son 
Jonathan came down and erected his first engine at Wheal 
Virgin, about 1743. The fourth son of Joseph was Jonathan 
Carter, the inventor of the compound engine and the double- | 
beat steam-valves, who died at Penrhyn in 1815. 
From 1720 to 1740 few engines were erected in Corn- 
wall because of the high duty on sea-borne coal. In 1741 
an Act of Parliament was passed for the remission of the 
duty on coal used for fire-engines for draining tin and 
copper mines in the county of Cornwall.‘ The effect of the 
passing of this Act was that by the year 1758 many 
1 It is curious to observe that the first engine was erected for Mr. Back 
through the influence of a Mr. Potter. Mr. Norris writes that John and 
Abraham Potter were engineers in Durham, and erected an engine for Mr. 
Andrew Wauchope in Midlothian in or about 1725. See also Bald’s ** View 
of the Coal Trade of Scotland,” pp. 18, &c., for a full account of this engine. 
He prints the contract in full, giving many interesting details. 
2 A drawing of almost the first Watt engine for the Birmingham Canal 
was illustrated in the Exg7neer, July 15, 1898. This is now erected in the 
yard at Ocker Hill, near Wednesbury. 
3 The Act referred to is the 14th Geo. II., Cap. xli., and intituled :—An 
Act for granting to His Majesty the sum of one million out of the sinking 
fund, and for applying other sums therein mentioned for the service of the 
year 1741; and for allowing a Draw-back of the Duties upon Coals used 
in Fire Engines for drawing Tin and Copper mines in the County of 
Cornwall, &c¢ 
NO. 1777, VOL. 69] 
became | 
in popular | 
engines had been brought into use; one engine at Herland 
had a 7o-inch cylinder. 
Rotative Atmospheric Engines.—It appears that attempts 
were made as early as 1768 to produce a rotative motion 
from a Newcomen engine, but it was not until about 1780 
that it was successfully accomplished by the use of the 
crank. 
It does not appear that any attempt was made, before 
Watt’s separate condenser was invented, to reduce the cool- 
ing effect of the injection-water on the cylinder by effecting 
the condensation in a small vessel attached to the cylinder. 
It is, however, evident that after Watt’s patent, Newcomen 
engines were made with separate condensers without air- 
Fic. 1. 
RELATIVE COAL CONSUMPTION 
FOR A 
GIVEN RATE OF EVAPORATION. 
NEWCOMEN 
CORNISH 
1800 
MODERN 
1850 
1712 1776 1900 
INCREASE OF STEAM PRESSURE 
CORNISH MODERN 
1300 Oo 
NEWCOMEN 
W712 73OT# BY 
1776 
Fic. 2. 
Diagrams illustrating the progress in economy of fuel and the increase 
of steam pressure. 
pumps, the air being discharged through a snifting-valve. 
Such condensers were known as “‘ pickle-pots.”’ 
In Fig. 1 will be found a sketch of the ‘ pickle-pot ’’ 
condenser. Such condensers were operated without air- 
pumps, as already described. It is more than probable 
that such condensers were not known until after Watt’s 
invention of the separate condenser, and that they were 
applied to improve the economy of the Newcomen engine 
and to evade Watt’s patent. 
In Fig. 2 will also be found a diagram constructed by 
the author to indicate the economy of fuel resulting from 
various improvements commencing with the earliest 
engines of Newcomen.. A diagram below also indicates 
rs 
