[LB014345], Letter from Thomas Alva Edison to Theodore Turrettini, October 27th, 1882


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[LB014345], Letter from Thomas Alva Edison to Theodore Turrettini, October 27th, 1882

Editor's Notes

We are sending you by Wells Fargo & Co. Express the Patent office drawings relating to Electric Railroad together with working drawings of Passenger Locomotive, Electric Bar, and the [Form Faire]. The drawings of the [--panning] [---] are now under way and will follow in a few days.##To prepare the rails for laying, the [web] for six inches from the end on both sides shuld be made smooth by filing or by using a milling machine. Then immerse in good baking Japan leaving the top or [tread] of the rail bars. All bad spots should then be touched up with a brush and the ends [cleaned] and brightened with Borzine and allowed to stand long enough for the [---] to set in the air after which it is ready for the baking oven. If the Japan is too thick it should be diluted with a reducing special compound of three parts [tirpentine] and one part extra [qu--- -ap--a]. The oven should be heated to 320 F. and the rails left in about six hours. The spikes and clamps should be treated the same.##The cloth, for insulating the rails from the ties, is prepared by drawing it through a box of Japan, thence passing between two half round blocks covered with velvet and the superfluous Japan is removed leaving a smooth even coat. The upper velvet block should be hinged so as to permit of the cloth being put between them with care.##By stretching the covered muslin strips in a frame made by driving pegs into blocks and keeping the blocks the desired distance apart by nailing strips to them and stretching the frame in the oven enables us to get a large quantity in at one time and to bring it out smooth.##The rails clamps spikes and cloth should all have two cotes of Japan at least and three would be better.##In stringing the wires we find the best way is to put them under the first plate screw the nuts almost up and have two men stretch them tightly by means of a bar stuck into the ground while a third tightens the nuts and so hold them in place.##By keeping the [vices] on the [-t--ds] of the rails around curves they will accommodate themselves to the bend of the rail and will not be noticed and consequently [---] be liable to be disturbed.##In laying the tracks [four] thicknesses of the Japaned block should be used and the more the cloth covers the surface of the tie upon which the rail rests the better.##In putting the cloth under the rail we prevent [maiming] the insulation by using a wooden lever for raising the rail with several thicknesses of Japaned cloth between the lever and rail while raising it.##We find that putting the clamp into place on the [foot] of the rail and driving the [toe] of it into the tie before driving the spike disrupts the insulation very little if any.##The track can always be lined from the end of the tie [without] touching the rail##We found that the copper strips under the fish plates after long exposure to the weather become oxidized and [insured] the resistance of the rail at the joint and to improve this we had recourse to the plan shown in Patent office drawing marked No 476 of running two continuous wires on one side of each rail and the short strip on the other side. By adopting this plan we reduce the evil effect of bad contact at any one joint to the minimum, as the rail gets its current from the first joint where good contact is made where nothing but the short strips at the joint were used if one joint happens to be bad the resistance of all the track beyond that joint was very much insured.##The [gauge] of our wheels is 3' 5 1/2" and of the track 3' 6 1/2" on Straight track and 3' 7" around curves and we find that the cars move easily with no binding on the curves and it is perfectly safe as the wheels is 3 1/2"##I send with the other drawings a sketch of the box we use for Japanning the cloth.##The insulation of our two miles and a half varies of course with the weather but have never fallen below 100 ohms.## On account of counter currents from the track itself it is very difficult to make accurate measurements of the resistance between the tracks by the ordinary methods and we have found the best way is to break one of the cables with a plug putting a lamp across the opening made by running the plug and [noting] the light it gives.##Then put another lamp across the two lines inserting enough resistance to make both lamps alike and the extra no sixteen put on [circuit] with the lamp across the line as the resistance between the tracks##We have succeeded in making our joints so good that the drop in Electromotive force at the end of our [six] and a half miles of track only makes a difference of 20 Revolutions of the Armature of the motor between the extreme end and where the cable are [----ed] to the track which is very good considering the fact that our rails only weigh 16 lbs per yard and that we only use two No. [--] wires on one side of each rail and two short strips of flat copper on the other side.




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Thomas A. Edison Papers, School of Arts and Sciences, Rutgers University
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