"Figs. 2, 3 and 4 show various modifications of the method of applying the conducting powder to the stem. The process has since been further refined and perfected."
Pollard's idea was to replace the usual platinum leading-in wires with films of silver. Quoting from The Electrical Engineer4:
"The leading-in wires in this lamp are replaced by a conductor formed by depositing upon glass a line of silver or other metal in powdered form and then heating the glass sufficiently to cause the metal to adhere to it. The line of minute particles thus embedded in the surface of the glass forms a conductor for the electric current. In embodying this principle in a lamp, as shown in Fig. 1, the interior surface of the tubes 3 3 is coated with sizing, and upon this sizing there is sprinkled fine silver powder, after which the tubes are heated sufficiently to cause the particles of silver to adhere firmly to the glass, the sizing serving to hold the powder in position upon the glass until the glass is raised to the temperature necessary to cause the powder to adhere thereto. While the glass is hot the stem is pinched until its opposite walls come in contact and become welded together, Fig. 1a, thus forming a seal. The ends of the carbon filament are attached within the ends of the glass tubes by carbon paste. The conducting-wires 5 5 are connected by cold-pinching them within the tubes 3 3, having the wire in contact with the silver, as shown in Fig. 1. The silver particles thus united with the glass form a conducting connection between the conducting-wires and the carbon filament.
"According to the inventor the best method of obtaining the silver in powdered form is to dissolve the silver in nitric acid and then suspend pieces of copper in the solution to cast down the silver in a very fine powder. The silver is then thoroughly washed and passed through a fine sieve. The sizing used to attach the powder to the glass is made by mixing together copaiba balsam (two parts) and fir balsam (one part.) "Figs. 2, 3 and 4 show various modifications of the method of applying the conducting powder to the stem. The process has since been further refined and perfected."
It is not known by this writer how many different companies manufactured the Pollard lamp. One such lamp, owned by Jerry R. Westlick has a "Packard" label. If the lamp was made in the United States it is traceable to The New York & Ohio Co., of Warren, Ohio. If it was made in Canada it probably came from the Packard Electric Co., Ltd., located at St. Catherines, Ontario. The three Pollard lamps in the Hammer Collection12 (1894-455; 1894-457; 1894-461) were made by the Imperial Electric Manufacturing Company. Pollard lamps were also made by the Buckeye Electric Company3,4 of Cleveland, Ohio and the Boston Incandescent Lamp Company5,6,7,8.
Pollard was a resident of Cambridge, Massachusetts and worked as a glass etcher. This writer is not familiar with that profession and so the word "etcher" was looked up in Webster's New World Dictionary, Third College Edition. The definition found there was:
"1 to make (a drawing, design, etc.) on metal, glass, etc., by the action of an acid, esp. by coating the surface with wax and letting acid eat into the lines or areas bare with a special needle 2 to prepare (a metal plate, glass, etc.) in this way, for use in printing such drawings or designs 3 to depict or impress sharply and distinctly —vi to make etchings—etcher."Pollard's wife was Martha W.11, and she was the administratrix of his U. S. Patent No. 485,478, issued Nov 1, 1892. The only other patent known to have been granted to Pollard was No. 402,476, for a vapor burner for stoves, granted Apr 30, 1889.
Acknowledgements
The writer thanks Joyce Syphers, of New Hampshire, for permission to use photographs taken by her of a 63-volt, 16-candlepower Pollard lamp. Jerry R. Westlick, of Ohio, also contributed knowledge and photographs of his 52-volt, 16-candlepower Pollard lamp. The Cambridge Public Library kindly found and supplied information about the Pollards in their City Directories. The Public Documents and Patents Department of the Cincinnati Public Library is always a source of instant response and information. The sharing of information allows these early lamp efforts to be better understood and appreciated.
References and Bibliography
1) U. S. Patent No. 485,478 granted to Edward Pollard, Nov 1, 1892.
2) Minutes Book of the Board of Directors of the Buckeye Electric Company, Oct 26, 1893.
3) "The Buckeye Lamp Without Leading-In Wires", The Electrical Engineer, Vol 17, No 297, Jan 10, 1894, pg 25.
4) "The New Buckeye Lamp Without Leading-In Wires", The Electrical Engineer, Vol 17, No 298, Jan 17, 1894, pp 55-56.
5) "General Electric vs. Boston Incandescent Lamp Company", Electricity, Vol 6, No 14, Apr 18, 1894, pg 180.
6) "The Pollard Lamp", Electrical Review, Vol 24, No 17, Apr 25, 1894, pg 201.
7) "The Pollard Lamp", The Electrical World, Vol 23, No 20, May 19, 1894, pg 679.
8) "The Decision Against Powdered Silver Leading-In Wires", The Electrical Engineer, Vol 17, No 320, Jun 20, 1894, pg 538.
9) "The Boston Incandescent Lamp Company Defeated", Electrical Review, Vol 24, No 25, Jun 20, 1894, pp 302-303.
10) Our Boston Letter, Electrical Review, Vol 24, No 25, Jun 20, 1894, pg 303.
11) Cambridge City Directories, 1889-1893.
12) The William J. Hammer Historical Collection of Incandescent Electric Lamps, which is housed at the Henry Ford Museum, Dearborn, MI.