Steam has been a fascination to many inventors over the centuries. Amongst the earliest records can be found that of Hero of Alexandria who played with a device that could be called an early turbine. He called it the “aeolipile” – it was a sphere into which steam was fed from a boiler (really just a kettle as it worked at very low pressure) with bent pipes exhausting the steam and causing the sphere to rotate.
Others along the way experimented with devices that used heat from a fire or solar, to expand air to make a variety of devices work or move. But this was not steam power.
The following history traces the major steps in steam use and efficiency improvement through various forms of industrial use, agriculture and transport. These steam power modes were interwoven in their development as engineers and inventors picked up on new ideas and modified and made them more appropriate to whatever their pressing need.
The requirements of different forms of transport and steam power vary widely and drive engineers in different directions. For example:
- a railway locomotive is limited in size due to the gauge of the track; to obtain sufficient power the cylinders may be compounded or multiplied in a number of ways; weight is important for traction; condensors are largely impractical on mobile engines.
- A steam ship requires that it’s centre of gravity remain low in the hull; speed of the engine is generally quite slow to avoid the need for gearing; weight is not the same problem in a ship as it is on say a truck.
- In road vehicles the boiler and engine need to be very light and compact creating difficulties in obtaining sufficient power from a very small space.
Cross pollination of ideas from one form to another created a healthy atmosphere of competition in the most part. It was not until the 17th Century that things started to move and improve the way steam (water vapour) could be used.
In 1629, an Italian engineer Giovanni Branca is credited with the invention of the impulse turbine. He boiled water in a small retort and the jet of steam from the constricted outlet, blew onto a small turbine to drive a small stamping mill. He was frustrated by the lack of technology to help him create steam at a useful pressure and another 250 years were to pass before Charles Parsons took up the development of the turbine.
The main technology that was lacking was in the ability to make steel plate for boilers. In 1642, another Italian , Evangelista Torricelli, demonstrated the vacuum. This was the impetus for recognising that work could be performed by steam – not directly, but by creating a pressure difference that allowed atmospheric pressure to actually do the work required.
In 1690 a Frenchman Denis Papin used steam as a means to form a vacuum by admitting steam into a chamber and then condensing it in his miniature “Piston in a Cylinder” to drive a small bucket pump. It was tiny and hindered still by lack of boiler capability.
Then in 1712, an Englishman Thomas Newcomen took the process further by making a boiler that was a separate device, and condensed the steam in the cylinder using a water spray. This process drove a single acting piston which raised water to drive a water wheel to produce rotary motion. Up to this stage, steam was produced in kettles or large copper vessels and it was not until 1725 that iron plates were successfully hammered flat to provide material for primitive boilers working at low pressure.
In the meantime, Newcomen’s pumping engines reigned, still in their basic format, until in 1765, James Watt invented the separate condensor. Soon afterwards, Watt “put a lid” on the top of the cylinder so that steam could be used on both sides of the piston. This was still at low pressure which required the formation of the vacuum.
Soon after in 1769 Nicholas Cugnot in Paris constructed the first full size, mechanically driven vehicle.
A major improvement then came about, not directly through steam utilisation, but by the ability to machine the bores of brass or cast iron cylinders, which up to this point in time had been hand finished after casting. John Wilkinson invented the boring machine and he then had a monopoly for several years on the patented process to cast and machine cylinders. It was to be 1776 before James Watt produced his first pumping engine – with a 1.27met diameter piston.
The crank was invented by James Pickard who patented the device in 1780 which prevented Watt and others from using it until 1794.
John Hornblower took the next big improvement in steam utilisation by introducing compounding in 1781. Compounding takes the steam exhausted from one cylinder and introduces it into the next (generally larger diameter) cylinder at a lower pressure and in doing so generates a big energy efficiency and therefore fuel reduction. In these days we would hail it as an emission reduction.
In 1784, an American, James Rumsay, saw the benefits of applying steam to water transport and after trying to make a pole driven boat, he invented the first jet boat where steam from a boiler drove a reciprocating pump to force water out at the stern of the vessel.
Boilers were still restricting the power outputs of the various machines as the technology for making steel plates for boilers was lagging the mechanical development of engines.
In 1880 many of the patents held by James Watt expired. These patents had been restricting the work of other inventors and engineers, and from here onwards, developments went ahead in leaps and bounds – all aimed at improving steam efficiency and fuel reduction. For over 30 years pumping engines grew in size and therefore output.
The earlier pumps were applied to the dewatering of tin mines in Cornwall, but they then found duty in town water supplies as well as sewerage. Cylinders up to 80 inch (2.03 meters) and even 100 inch (2.5 met) diameter were built and pump outputs up to 125 million gallons per day were achieved. That is the equivalent of over 27000 tonnes per day or more than 1100 tonnes per hour! They were not little machines!
Another Frenchman, Marquis de Jouffroy, in 1783 built the first successful steam powered boat and demonstrated it by steaming upstream on the Saone River. This vessel, the Pyroscaphe was driven by one double acting cylinder engine operating a ratchet and pawl mechanism which drove side paddle wheels. The first commercial steamboat, however, didn’t appear for another 24 years.
Next Page – History of Steam 1800-1900