Publication: The Telegraphic Journal and Electrical Review
TELEGRAPH CONSTRUCTION IN THE
By R. G. B. DAVIDS, Telegraph Engineer, Paulista Railway
Associate of the Society of Telegraph Engineers.
IN 1876 I was sent for from the Southern division of the English Postal Telegraph Service to take charge of the telegraph system of the Paulista Railway, Sao Paulo, Brazils. I left England under the impression that Siemens' iron poles were in use on the line, but great was my disappointment when, instead of seeing nice straight lines of iron poles, I found the most miserable erections I had ever seen. The poles were of wood, and of all shapes and sizes, set at various angles in the ground, and so crooked that they might fairly be compared to a corkscrew, whilst the wire, instead of being well stretched, hung in festoons of various dips, and in many places touching the ground.
I at once commenced making notes of pole roofs, stays, earth wires, &c., but found after all that these miserable looking lines were the best that could be made under the circumstances.
Owing to the wood of the country rotting so quickly (in the usual place just below the ground line) it was a useless expense to fit up a pole as in England, for every three years, at the outside, the entire line had to be renewed; in one case the greater portion of the poles on a line of sixty kilometers had to be replaced after having been erected only one year.
This set me devising all sorts of means for the improvement of the line, amongst others, the splicing of the poles at the foot with sound timber, the bolting of the poles to pieces of rails, &c., but I gave all these ideas up, as the expense would have been greater than the advantage gained, as I found that the poles in a short time tended to decay, generally over the whole length of the line.
As each pole cost three milreis (six shillings) and had to be renewed so often, I came to the conclusion that it would be far cheaper to send home for Siemens' iron poles, and renew the whole line at once, but this the Company did not feel inclined to agree to, owing to the larger prime cost of iron over wooden poles. I should state that our line of railway consists almost entirely of curves, not curves such as are made on an English railway, but very much sharper, many of only nine hundred feet radius; the opinion of Brazilian engineers being that it is cheaper to make enormous deviations, and run miles away from the direct line, than to make cuttings and embankments. The greater portion of the line also runs through forests, with only a few metres clearance on either side of the track; for this reason, in order to keep the wires clear of the branches of trees and the tropical underwood, as many as from twenty-seven to thirty-two poles per mile have to be employed in some sections. Thus it will be seen that the question of the cost of maintenance of the poles required serious consideration.
The rails employed on the line are of the Vignoles type, twenty-one and twenty-four feet in length; of- these there were lying in various localities hundreds, worn out and of no further value, even as old iron, owing to the great cost of transport to England.
Here I fancied there was what I required, but the question was at how little an expense and in what way were these to be employed?
Without a base plate, I at first thought that a rail would not support itself in the ground, especially on the sharp curves and soft banks, but I found upon experiment that this idea was unfounded, as a rail punned into a hole only three feet six inches deep, when blocks and tackle were attached to its top and pulled, bent to an angle of about sixty degrees and then cracked across, just below the ground line, without coming out of the ground.
The insulators employed on the line are Messrs. Siemens' iron hooded inverts, through the hooks of which on five poles the wire passes freely, being stretched and wedged at the sixth. These insulators I proposed bolting on to the rails, but to Mr. W. J. Hammond, the Locomotive Superintendent and General Manager of the line, I am indebted for the idea of the very simple, cheap, and admirable arrangement by which they are now fastened, and which I will endeavour to describe.
The rails are sent into the workshops where they have two 3/4 in. holes drilled about 1 in. deep, on the top face, the first being 12 inches from the top of the rail, and the second 16 inches from the first. Another hole, 1 inch in diameter, is at the same time drilled through the side of the rail, 18 in. below the second hole: this is for the purpose of fastening the stay wire, and is drilled 18 inches below in order that room may be left for the fixing of a third insulator, should such at any time be necessary.
Into the holes on the face of the rail are driven pegs, cut from 3/4 in. bar iron, these pegs are allowed to project about ½ in. Upon them the insulators are set, and are fixed in position by means of an iron hand formed to clip the sides of the rail and driven over the plate of the insulator. I give a rough sketch of a rail with the insulators attached, which will perhaps make my description more clear.
The pegs and insulators are fixed on the line before the rail is erected, the bottom band being slipped on before the top peg is driven in, otherwise it would not pass it.
The rails are put six feet into the ground, and well punned, being lifted into their position by mans of shear legs and blocks.
The holes are made by two tools, called respectively the "cavadeira" and the "enchada." The cavadeira is exactly similar to a very large flat carpenter's chisel, 8 in. long by 3-1/2 in. across, fixed to a long handle; it is employed to break the earth. The enchada, a tool very similar to a Spanish spoon, is employed for clearing out the earth broken by the cavadeira. Marshall's earth borers would be far preferable to these tools, and I intend giving them a trial. When they arrive I expect to do the work of making the holes twice as fast as at present.
The stretching poles are stayed on either side, in the line of the wires, to prevent their being over, in case both wires are broken at once by the falling of trees, &c.
When stretching the wires, the stay which supports the strain is only temporarily punned. When the wires are pulled up at the next straining pole the stay at the last is left very slack, the stay-block has, therefore, to be sunk deeper.
For stay wires I employ strand signal wire, and for stay blocks, old fire bars rejected from the engines, short pieces of rail, or, in fact, any old scrap iron.
The rails, when erected, are tarred all over, and as coal tar in this country dries like black varnish, it gives them a very good appearance.
As we are now passing through the rainy season they are having a rather severe trial, but I am happy to say there is not the least appearance of any one rail having sunk, or gone over, in the slightest degree.
The railway company, with which this line is in connection, being about to employ their old rails in a similar manner, I am induced to send this short description in the hope that it may prove of value to others who may be placed in a similar position to that in which I found myself.