“The cover this week shows an intake gantry at the works on the Bonneville Dam, Tennessee, USA. The dam is part of a huge project designed fro navigational purposes, for the control of floods and for the harnessing of water for a hydro-electric power scheme.”
A chapter dealing with many of the irrigation schemes in Australia, and describing the building of the huge Burrinjuck Dam in New South Wales. The article is by Harold Shepstone and is concluded from part 13. It is the fifth part in the series on Triumphs of Irrigation.
Electric Power from Steam
One of the largest power stations in the world, in which electricity is produced by steam turbines, has been built on land reclaimed from the waters of Lake Michigan, North America. In this chapter F E Dean describes how electricity is produced from coal at the huge State Line Power Station at Chicago. This great steam-driven power house has been planned to have a capacity of 1,000,000 kilowatts.
Spillway on the Burrinjuck Dam
“TWO SPILLWAYS were provided, one at either side of the Burrinjuck Dam. They are nearly at the same level as the crest of the dam. The spillway channels are carried some distance below the dam and turned inwards, so that the two streams meet and neutralize their respective scouring actions. Burrinjuck Dam has formed a lake with a maximum depth of 200 feet and a water area of 12,780 acres.”
AT first sight the locomotive illustrated below does not, judged by modern standards, look anything out of the ordinary, but it is, nevertheless, an interesting and unique engine. The running parts are, in the main, those of a 4-6-0 express locomotive of the German
It is well known that greater fuel economy is obtained as boiler pressures are increased; but the use of exceptionally high pressures involves, first, difficulties in construction and, secondly, trouble from scale deposited by the feed water on the heating surfaces. In this engine the steam from the boiler working at the highest pressure is not used directly as motive-power, and no feed water is introduced into that boiler.
The boiler consists of a number of tubes arranged in the form of a rectangular box and constituting the walls of the furnace. The tubes are, virtually, closed rings, part of which pass through the water of the second boiler. Steam at a pressure of anything between 1,100 lb and 1,300 lb per sq in is generated in the furnace part of the tubes and thence passing into the upper part immersed in the water of the second boiler. Here the steam, in giving up heat to
that water, condenses and returns to the furnace part of the tubes to be evaporated again; the cycle is continuously repeated. The water in the first boiler is chemically pure and does not need to be added to unless some part is lost through the safety valve or by leakage. There
is thus no chance of scale being deposited in the tubes.
Steam is generated in the second boiler at a pressure of 853 lb per sq in and this steam is drawn off in the usual way. The third boiler is virtually the barrel of the ordinary type of locomotive boiler, that is, it is a drum in the water space of which are a number of longitudinal horizontal tubes forming the passages between the furnace and the smoke box.
The steam from the second boiler passes, by way of a superheater in the upper tubes of the third boiler, to the single high-pressure cylinder. The exhaust from this cylinder, because the inlet steam is at 853 lb per sq in, is naturally at a comparatively high pressure and, instead
of being discharged up the funnel in the usual manner, it is led into a header which also receives steam from the third boiler at a pressure of 199 lb per sq in.
The mixed steam is passed through a superheater in the lower tubes of the third boiler and is then taken to the two low-pressure cylinders. The exhaust steam from the low-pressure cylinders is led through a feed water heater situated on top of the smokebox in front of the funnel. A large part of the scale is deposited in this heater, the water being drawn from the tender, and the heated, and largely purified, feed water is delivered to the third boiler. The feed water for the second boiler is taken from the third boiler, the transfer being made by a high-pressure pump.
In this way it was expected that the difficulties due to scale would be eliminated and that the economies arising from the use of exceptionally high pressures would be obtained. The locomotive has a wheelbase of 30 feet. The driving wheels are 6 ft 6 in in diameter, and the
bogie wheels are of 3 ft 3⅜ in diameter. The grate area is 27 sq ft. The high-pressure cylinder is 11 7/16 in and the two low-pressure cylinders are 19 11/16 in. in diameter. All three cylinders have a stroke of 24 13/16 in. The weight of the locomotive in working order is 89.2 tons.
The engine was tested on eleven runs varying between 70 miles and 101 miles, the track being virtually level. The trains hauled varied in weight between 454 tons and 760 tons and the speeds between 55 miles and 62 miles an hour. The object of the tests was to find out how far the performance of this type of locomotive could be improved by the new design of boiler. A saving of about 20 per cent in the fuel consumption was effected. After four months' running the only scale present in the second boiler was a fine loose dust easily removed.
It may seem strange that an old engine should have been used for this experiment instead of a new one, but this procedure embodies the scientific principle that, in making an experiment, only one factor should be varied at a time. If the running gear of the engine had been altered as well as the boiler it would have been impossible to say which of the two was responsible for the improvement.
“STATE LINE POWER STATION is so called because it lies across the boundary between the States of Indiana and Illinois, at Hammond, near Chicago. Lake Michigan is the source of the water which is turned into steam to drive the turbines. About 73 acres of land were reclaimed from the lake to form the site of the power station.”
The Victoria Falls Bridge:
“THE CENTRAL ARCHED SPAN of the Victoria Falls Bridge measures 500 feet. It is flanked by two straight spans of braced girders, that on the north bank being 62 ft 6 in long and that on the south bank 87 ft 6 in long. The arch is formed by two arcs side by side and inclined inwards. The main girders are 27 ft 6 in apart at the upper ends and 53 ft 9 in apart at the abutments.”
Conquest of the Rockies
The building of the Canadian Pacific Railway across the muskeg swamps and prairies, over the foothills, and through the forbidding range of the Rocky Mountains was one of the finest epics of the pioneers of engineering. Many famous books, and at least one or two recent films, deal with romantic and epic stories of the pioneers of engineering. The building of the Canadian Pacific Railway, for instance, is one of these epic stories of the engineers’ fight against Nature. It is now possible to travel by train across Canada from the Atlantic to the Pacific. It has been possible for many years, and because such a journey is now a commonplace it becomes all the more exciting to read the story of how that line was forced across uncivilized country and over the terrific mountain barrier of the Rockies. In this chapter the story of the Canadian Pacific Railway is told by D Wilson MacArthur. He describes the expeditions which carried out the preliminary surveys and finally selected the most practicable route by which the railway could be carried from eastern Canada to the shores of the Pacific. No detailed maps existed. The surveyors had to fight their way through dense forests and across mountain ranges where few white men had ever ventured before. Twelve thousand men were chosen to build this great railway through swamps, vast prairies and mountains. To add to the difficulty of surmounting almost incredible natural obstacles, there were all the rigours of Arctic blizzards, and the dangers of attack from Indians and wild beasts. This is the fourth article in the series on Railway Engineers at Work.
“TWIN AIR-LOCK in the tunnel, showing shifting rails for entering the lock chamber. The north tunnel, for railway traffic, was equipped in 1903 with a cable-hauling system. This was built in three independent sections, separated by the air-locks. The first section, 1,575 feet long, reached from the foot of the shaft to the first air-lock. The second section, 1,660 feet long, connected the first and second air locks. The third section, of variable length, extended from the second air-lock to the working face. The object of the air-locks was to prevent the compressed air from gushing into the shaft from the workings. Air locks were installed also on the south tunnel.”
Tunnelling the Hudson(Part 1)
For thirty years obstacles baffled and tragedy thwarted all attempts to complete a tunnel beneath the Hudson River, New York, but at length the engineers achieved a lasting victory over the forces of Nature. This is one of the most amazing stories of engineering. The chapter on this subject is by David Masters. The Hudson Tunnel was begun in 1874, but thirty years of frustration, tinged with tragedy, were to elapse before it was completed. The article is concluded in part 15, and is the third article in the series Below the Surface.
The Connaught Tunnel
“THE CONNAUGHT TUNNEL, five miles long, was built under Mount Sir Donald [sic] in Rogers Pass. A new method of tunnelling was adopted for the first time in building this tunnel. A pioneer bore, or small tunnel, was driven first about 50 feet to one side of the main tunnel and galleries were driven out to the line of the main tunnel. By this multi-bore method the main tunnel was excavated in 704 days.”
This illustration forms the end of the photogravure supplement to this part.
The Victoria Falls Bridge:
Photogravure Supplement 2
“THE FINAL STAGES. The centre panels of the arch were completed on March 31, 1905. The ends overlapped by only 1¼ in, but when the engineers came to complete the work next day they found that contraction during the night had caused the ends to meet with precision.”
The Victoria Falls Bridge:
Photogravure Supplement 3
“1,500 TONS OF STEELWORK were used in the Victoria Falls Bridge. The bridge was built at Darlington, Co. Durham, and assembled there in sections to ensure that every component was perfect. Then the sections were conveyed to the heart of Africa by sea and by rail. At one time there were 400 natives working on the bridge.”
A Wooden Trestle Bridge in the Selkirk Mountains
“EARLY WOOD-BURNING LOCOMOTIVE hauling trucks across a wooden trestle bridge in the Selkirk Mountains. Wood was used extensively, for sleepers, bridges, fences and the like, as well as for fuel. Locomotives had spark-arresting chimneys to prevent the danger of sparks which might have set alight the huge forests on either side of the line.”
Son of a Scottish farmer millwright, William Murdock proved his worth and versatility during his long association with the firm of Boulton and Watt. Murdock is chiefly remembered for his invention of coal gas lighting.
RIGHT-HAND man of the great James Watt, William Murdock was endowed with abundant talent and contributed much to engineering history. His well-deserved fame, however, has been largely obscured by that of his illustrious employer. In Watt's service, and in that of his successors, nearly the whole of Murdock's working life was spent.
William Murdock, the son of a farmer millwright of a hamlet near Old Cummock, Ayrshire, was born in 1754 and, after a period spent in herding cattle, was brought up in his father's trade.
The work was miscellaneous and called for inventiveness. Thus he was employed to build a bridge across the River Nith, near Dumfries. At the age of twenty-three, having learnt that a new type of steam engine was being manufactured by the firm of Boulton and Watt, he journeyed to Birmingham in search of a job. Fortunately for him, Watt was absent when he called, for the great engineer had told Sir Walter Scott that Scotsmen did not make good mechanics; the Clyde to-day could tell a different story.
Matthew Boulton, Watt's Partner, interviewed the young man who stood shyly in front of him hat in hand. That hat after a while attracted Boulton's attention; it seemed to be painted. Examination showed it to be made of wood and turned, as Murdock said, on a lathe that he had made himself. A lathe that can turn an oval shape such as is required for a hat needs both
considerable knowledge to design and skill to build. Boulton, having recognized this, gave Murdock a trial, ultimately engaging him for two years at 15s a week, with an extra 2s when
Once installed, Murdock quickly proved his worth. He was sent to Cornwall in 1779 to erect Watt engines at the mines, of which by the summer of 1780 some twenty were at work. This
task was not easy, as the Cornishmen were for the most part hostile, because they considered the dues charged for the engines excessive. Murdock, however - industrious, conscientious and loyal - eventually succeeded where Watt himself had failed, and when he left Cornwall in 1798 his loss was sincerely regretted by the miners.
During this Cornish period, Murdock made an invention from which has arisen a great modern industry, and he came near to being the first to create the locomotive. In his leisure time
Murdock built a model steam carriage which, though only small, proved powerful and speedy -so much so indeed that on one occasion it outran its inventor and gave a bad fright to the
Vicar of Redruth, who met it in the dark. Had Murdock persevered in this direction he might have anticipated Trevithick with the railway locomotive, but his efforts were frowned upon by
Boulton and Watt, as they feared that his attention would be directed from their pumping engines. The model was working between 1782 and 1786.
Murdock's other invention - lighting with coal gas - met with a better fate, though it brought him no monetary reward. One or two investigators had previously found out that the gas driven off by heating coal was inflammable, but it was Murdock who first made practical use of the phenomenon. In 1792 he had lighted his house at Redruth (Cornwall) with gas and had even made use of portable gas lanterns. In 1794, when on a visit to Soho, Birmingham,
he urged that the matter be taken up and gas-lighting patented, but the invention was allowed to remain dormant. In 1801 a Frenchman proposed to light a Paris street with gas, and this started Murdock on fresh investigations. In 1802 gas lighting was introduced at the Soho works, and the manufacture of gas-making plant was begun there in the following year.
This step enabled Boulton and Watt to contest a patent taken out by a German in connexion with a scheme for lighting London, and it was not until 1807 that the new illuminant made its
appearance there. After that year the use of coal gas for lighting spread rapidly. What the industry has developed into may be gathered from the account of the activities of the Gas
Light and Coke Company, which is given in the chapter beginning on page 59. Murdock's part in the introduction of gas lighting was not, however, entirely unrecognized, as in the year 1808 he was awarded the Rumford Gold Medal by the Royal Society for his paper upon the subject.
Murdock is credited with the invention of the sun-and-planet gear for converting a reciprocating into a rotary motion. This ingenious device Watt was driven to adopt when he had been
forestalled by the patent of a rival in the application of the simple crank to the steam engine. Murdock invented the transmission of parcels by compressed air, a device still used by the
Post Office and by large stores. He used compressed air as a motive power in a number of other ways, such as a lift for handling large castings.
Boulton died in 1809 and Watt in 1819, but for some time the firm had been carried on by their sons, Watt having retired in 1800. Murdock, although lamenting the loss of his two
friends, as they had become, did not sever his connexion with the firm, but continued to busy himself with all that went on almost up to the end of his life. Murdock died peacefully at his house, not far from the works, on November 15, 1839, and is buried near his friends at
“COAL-HANDLING PLANT at State Line Power Station is ingenious in design and expeditious in action. Coal emptied from the dumper (left) is fed from a hopper on to a 42 in belt conveyor which carries it up to the breaker house at a speed of 360 feet a minute. Here the coal is broken up by a battery of rotating drums, each with a capacity of 250 tons an hour. The broken coal is then carried up to a tower, about 100 feet high, by another conveyer. Thence it is carried to the boiler house or to the storage grounds.”
An outstanding feature of the Cape to Cairo route is the great bridge which spans the gorge of the Zambezi River below the Victoria Falls in the heart of Africa. The bridge was built in Great Britain and assembled at the site. It was part of the dream of Cecil Rhodes that Cairo should be linked to the Cape by railway. One of the greatest obstacles that such a railway had to pass was the mighty Zambezi River. Not far from the Victoria Falls, discovered by Livingstone in 1855, the Zambezi River flows through a deep gorge and across this gorge a slender single-span steel arch now carries the railway. The bridges itself is of outstanding interest and the way in which it was thrown across a deep gorge, miles from civilization, is described in this chapter. Every part of the bridge was built and assembled in Great Britain to ensure that every component was perfect. Then the bridge was shipped to South Africa in sections and carried to the hear of Africa to be erected there. One of the greatest difficulties was to find suitable anchorages, but in spite of all these difficulties, when the bridge had been put into position the ends of the central part of the structure overlapped by only one and a quarter inches. This was at sunset, but next morning it was found that the span had contracted during the night and the ends met with mathematical precision.
“A SINGLE-SPAN STEEL ARCH BRIDGE crosses the Zambezi River where it runs through a deep ravine below the Victoria Falls. The bridge was built to carry the railway across the Zambezi and the railway reached this spot in May 1904. In 1930 the deck was raised 5 feet and widened 13 feet to accommodate a motor road.”
One of the Four Anchorages
“ONE OF THE FOUR ANCHORAGES on which the feet of the single-span arch rest. The foot of the arch and the foot of the vertical end post are united by a bent plate and diaphragms and by the common saddle resting on the bearing pin. The bearing pin is carried in a forged steel cup fitted to the top of a pedestal bolted to the base plate, which measures 11 ft 6 in by
5 ft 10 in. The base plate reduced the load on the concrete support to 21 tons to the square foot.”