The Sawyer-Man Incandescent Lamps.

As before stated Edison fixed upon carbonized filament of bamboo. The Sawyer-Man company however applied for a patent on carbonized filament for incandescent lamps on January 19th 1880, and after five years litigation with Thos. A. Edison they were granted a patent No. 317,676, on May first, 1885, covering their invention. The Sawyer-Man lamp Fig. 25, consists of a carbonized connected to platinum wires fused in a glass tube from which all the air possible had been extracted. The light is produced by the glow of the filament and heat of gases given from filament. The life of a lamp is from 1000 to 1500 hrs. and requires a current of 1¼ to 1.3 amperes and give 20 to 25 C.P. When the filament becomes brittle and breaks the tube is unscrewed from the key Fig. 26, and a new one screwed in. They are run on the arc light circuit by the use of an individual distributor Fig. 27 which consists of a brass case containing a magnet in the circuit of the lamps and a resistance coil automatically substituted in case the lamp should break or is turned off by key Fig. 26. The scheme of arranging lamps so as to get the right current is shown at Fig. 28. the number of lamps in a group depending on the current.

Prof. Thomson has gotten out a lamp Fig. 29 in two styles one for 6.8 amperes current and one for 10 amperes current. Three lamps of different candle power, due to different potential differences at binding post of lamp, are use on the same current. The method of connecting them is shown in Fig. 30. It will be perceived that the lamps carry the full current yet have a life of 1000 hrs. or more. This is a great invention indeed doing away with a great loss of power due to high resistance coils. It will be noticed however that a 125 C.P. incandescent lamp uses as much energy as a 2000 C.P. arc light, the 65 C.P. lamp one half as much and the 32 C.P. lamp one fourth as much.

General Remarks

The Thomson Houston system also furnish lightning arresters, ammeters, hanging boards, switchboards, hoods, insulators, lamp arms, etc, but, though in some respects many of these miscellaneous articles are ingenious and novel, yet they are not distinctive of the Thomson Houston or any other system. Be it said however that all these articles fill their proper places. The company also furnish a motor to go on their circuits but for the double reason that of the motor not being strictly related to electric lighting and of being unable to obtain a description of it, it must remain undescribed as far as this thesis is concerned.

After describing all the parts of the system it may be interesting to know how a plant is arranged. The last plate is a photograph of the LaFayette Gas Company’s Plant of the Thomson Houston System taken at ten oclock one night. It shows the engine, dynamos, the wall controller on the left wall, and a view of the lamps which had hoods put before them to prevent the polarization of the negative.

On the accompanying page will be found a table showing experiments with an old style dynamo given Purdue University by the Thomson Houston Company, which dynamo is now in the engine house of the Mechanical Hall.

Experiments with Three Light T-H. Dynamo No. 79

The dynamo was run by a large pulley (about four and one half feet in diameter) on the same shaft as the fly wheel and beside the latter. Two lamps were put in circuit with a Deprez-Carpentier ammeter and a volt meter of the same make was put in between the brushes. First one lamp (old Thomson style) was switched out of circuit, the dynamo started and when speed was reached the circuit made. The following readings were taken when the engine made 139 & the dynamo 1122 revolutions per minute.

Readings At End ofOne LampTwo LampsWhen 2nd lamp was switched inWhen 2nd Lamp was switched out
Amp.VoltsAmp.VoltsAmp.VoltsAmp.Volts
1 second1055101106.75514110
30 "10551011010751085
2 Min105510110101091060
3 "105510110101101055