How Your Hobby Started Part XIX

Gasoline Engine

Carleton M. Mull

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390447th Avenue, S., Seattle, Washington 98118

Mention was made in the July-August Volume 6 issue of the Gas Engine Magazine of a rare make of engine by the Priestman & Co. of Philadelphia, Pennsylvania and also with offices and manufacturing plants in London, and Hull, England and Glascow.

From this article came several very informative letters from one of our readers, Anthony Harcombe, Esq., residing in Westcott, Surrey, England. He has a collection of expertly reclaimed antique engines including a Priestman, a Southwell, a Richard Hornsby, a Petters, a Fairbanks, Morse Type 'T' and others.

The 2 HP vertical, single cylinder Southwell is very similar to the Fair banks Morse Type 'T'. The difference is in the push rod for the exhaust valve, which on the Southwell has only one push rod. It actuates both the exhaust valve and the igniter, while on the Type 'T' there is a push rod for each of these functions. Also the Type 'T' has a gear driven low tension magneto as original equipment while the Southwell is equipped with a battery, choke coil and igniter.

As can be seen from the picture, the Southwell has a mixing valve mounted on top of the cylinder head, with an igniter located just below in a boss cast on the side of the cylinder. The governor and timing gear are located outside the closed crankcase and a rocker arm to operate the fuel pump. The fuel tank is located between the engine mounting skids

Plainly stated on a brass plate on the side of the crankcase hand hole plate is the fact that it was made in the U. S. A. After correspondence with a number of the well known engine collectors in our country, it has not been possible to trace any information concerning the the manufacturer of these engines. Undoubtedly it would be interesting to the readers of G.E.M. to learn more about the Southwell engines and should anyone be able to offer additional data, it will be gladly added in a future installment of this story.

The other very rare engine in this Harcombe collection is the Priestman. From the pictures it can be seen that this company built different types in this country than those in existence now in England. (With assistance of Dave Reed of Elsmore, Wilmington, Delaware reproduction of pictures of the Priestman engine catalog is shown in order that a comparison can be made of the Philadelphia engine and the one now in Surrey).

The details of the construction and operation can also be compared from the page of the Philadelphia catalog and Anthony Harcombe's letter; which is quoted here in its entirety:

Southwell 2 HP gasoline engine owned by Anthony Harcombe, Westcott, Surrey, England. The engine was made in U. S. A.


Anthony Harcombe Westcott, Surrey, England

Dear Carleton, I read with some interest, your mention, in a previous G.E.M. of the American Priestman engine, (Vol. 6, No. 4) because I have in my collection, what is believed to be, the only working example of this revolutionary machine. The only other survivor is in the Science Museum in London. They are of course the British design. I would be very interested to hear if any American ones still exist.

William Dent Priestman was born near Hull in Yorkshire in the year of 1847, educated at a Quaker School at York and was apprenticed to W. G. Armstrong & Co., later known as Armstrong Whitworth & Co.

His father started him in business at a small foundry in Hull in 1870 where he undertook general repairs to machinery of one sort or another.

He was a modest man but a man of great courage and perseverance. He fought for the abolition of slavery and was the instigator of the anti-bribery and corruption Act of Parliament. In the late 1870s he was determined to succeed where others had failed, namely to produce an engine which would run on 'common petroleum' or lamp oil. Hitherto engines away from a town gas supply had to either have expensive gas producers or be run on petroleum spirit, the handling and storage of which was made almost impossible by stringent safety regulations and insurance premiums.

Priestman 6 HP gasoline engine owned by Anthony Harcombe, Westcott, Surrey, England.

After some years of patient research he succeeded in producing a vaporizer assembly which was to be the focal point of his successful engine.

The patent for this was drawn out in 1885, at which time Rudolf Diesel was managing an ice works in Paris, and Herbert Ackroyd Stuart had only just begun experiments. Production was soon under way and the Priestman engine was exhibited at the Royal Agricultural Show in 1888 and won medals for three years running.

Operation of the engine was briefly as follows:--the fuel tank cast into the engine base, was kept pressurized at 8 to 10 lbs. per square inch by a piston pump attached to the exhaust valve push rod. Initial air, for starting, was provided by a hand pump behind the engine. Oil flowed via a dip pipe and a suitable lever valve, to the heater lamp for starting, and to the spray valve in the vaporizer. Also, via this valve air alone passed under pressure to atomize the fuel in the sprayer. The vaporizer chamber heated at starting by the lamp, is kept hot by the exhaust gas whilst the engine is working.

The vaporized oil passes into the cylinder through an automatic inlet valve and the charge is compressed and fired by a high tension spark.

The spark was provided by a system undoubtedly designed by French electrical engineer Eugene Eteve and was powered by a series of Voltaic cells. The low voltage circuit was made at the firing moment by a brass bell on the exhaust valve rod passing between two metal tongues allowing current to flow into a buzzer and high voltage trans former. The circuit being the same as the trembler coil ignition being fitted to new vehicles thirty years later.

Whilst my Priestman runs very well on a car battery, the original cells were unreliable, in constant need of attention, and very messy. The engine was there fore converted, probably by the makers at the turn of the century, to hot-tube ignition. The original electric apparatus was, fortunately for me, left on site.

No expense, nor come to that, any cast iron were spared during the manufacture of these machines. The three horsepower engine in 1888 was quoted as weighing over twenty hundredweights. Great simplicity of design combined with a very high standard of finish and fitting made the Priestman engine a legend in its  own lifetime.

Fairbanks Morse Type 'T' gasoline engine owned by Anthony Harcombe, Westcott, Surrey, England.

Mr. Philip D. Priestman, President of Messers Priestman Brothers, Hull, and son of the founder, informs me that a thousand of these engines were made from 1888 till about 1900 when production ceased.

Ackroyd Stuart's patent in the skillful hands of Messers Richard Hornsby & Sons of Grantham, was beginning to tell on Priestman's sales and this, coup led with the fact that their interests were turning to dredgers and excavators which have since made them famous, made them stop engine production.

My engine, which is about six horse power has a bore of 7?' and a stroke of 12', the weight being just over a ton. Engine speed between 190 and 200 rpm.

I discovered it lurking in an old pump house not five miles from my home and after a lot of struggling, two kind assistants and myself armed with ropes, boards, lorries, vans, etc., managed to get the thing home. But not before, I hasten to add, a five ton trolley jack had been crunched, a tow rope broken, a clutch partly incinerated and last but not least, a nose broken!

The engine is now finished, the work involved being mainly cleaning and rust removal, a few parts only, having to be made. The first time she was started, the procedure which should normally take twenty minutes, took at least three quarters of an hour, but with the aid of my wife, we won!

The chart 'D' on page 9 of the July-August 1971 issue gives the only specifications available on the size of engines built in this country by this company. Undoubtedly, they built other sizes as indicated by the fact that a different size bore and stroke is given in the above letter and which size is not listed in the U. S. specifications.

Priestman 6 HP gasoline engine showing construction details, owned by Anthony Harcombe, Westcott, Surrey, England.

System Operation

A. Oil tank filled with any ordinary high test (usually 150? test) oil, from which oil with air under pressure is forced through the B. Three Way Cock, and conveyed to the C. Atomizer, where the oil is broken up into atoms and sprayed into the D. Mixer, where it is mixed with the proper proportion of supplementary air and sufficiently heated by the exhaust from the cylinder passing around this chamber, from which it is drawn by suction through the Inlet Valve I into the E. Cylinder, where it is compressed by the piston and ignited by an electric spark passing between the points of the F. Ignition Plug, the current for the spark being supplied from an ordinary battery furnished with the engine, the G. Governor controlling the supply of oil and air proportionately to the work performed. The burnt pro ducts are then discharged through the H. Exhaust Valve, which is actuated by a cam. The I. Inlet Valve is directly opposite the Exhaust Valve. The J. Air Pump is used to maintain a small pressure in the oil tank to form the spray. K. Water Jacket Outlet.

By this system perfect combustion of oil takes place.

Priestman kerosene engine built at Philadelphia, Pennsylvania, circa 1892.

Table of Sizes and Dimensions

INDICATED HORSE POWERDiameterStrokeEfficiency of Mechanism Percent.Length Over AllExtreme WidthHeight Over AllWeight of Fly-wheel in poundsCapacity of Oil Tank in HoursApproximate Shipping Weight in pounds

Priestman kerosene engine ratings--built at Philadelphia, Pennsylvania.

Courtesy of R. F. Somerville, 12498 14th Ave. N., Haney, British Columbia, Canada.