Adjusting the Blake transmitter

"In adjusting the Blake transmitter, first, if the instrument is a new one, see that the paper padding is removed from between the carbon block and the frame

Next slack-back the adjusting screw till the platinum point is just clear of the diaphragm, then turn upwards two full turns. This will usually bring the instrument to the right adjustment. Place the telephone [ie: receiver] to your ear, however, and tap the diaphragm….if all is connected up properly, a sound will be heard in the telephone.

If the sound is dull and short , slack back the screw, but if it is inclined to be prolonged or make a humming noise, the screw must be tightened up a bit.

When properly adjusted a clear musical sound should be heard, but leaving off sharp.

Never at any time turn the screw more than a quarter of a turn at a time, as the best position is easily passed.

If the carbon button should be pulled back the platinum point should follow it nearly one half inch. Ina well-adjusted Blake transmitter breathing against the diaphragm should be distinctly heard, and in a quiet place, speaking in a whisper or the cawing of rooks on trees outside should be heard at the other end of the line." (Allsop 1891)

Resource material from:

A.C.T. The First Telephone , British Post Office Electrical Engineers Journal , Volume 25, 1932, pp116-117
Aitken, William Who Invented The Telephone? Blackie, London, 1939
Allsop F. C. Telephones Their Construction and Fitting, 1st Edition, E. & F. N. Spon, London 1892
Allsop F. C. Telephones Their Construction and Fitting, 2nd Edition, E. & F. N. Spon, London 1892
Baldwin F. C. History of the Telephone in the United Kingdom, Chapman and Hall, London, 1924
DuMoncel Count The Telephone, Microphone and Phonograph, Harper & Bros, New York, 1879
Hall, Elton W Francis Blake - An Inventor's Life, Massachusetts Historical Society, Boston 2003
Harlow, Alvin Old Wires and New Waves, D Appleton Century, New York, 1936
Herbert T. E. The Telephone System of the British Post Office, 2nd Edition, Whittaker, London 1901
Hospitalier, E The Modern Uses of Electricity, Volume 2: Telephone: Various Applications & Electrical Transmission of Energy, translated and enlarged by Julius Maier, Kegan, Paul , Trench & Co., London 1883
Kingsbury J. E. The Telephone and Telephone Exchanges: Their Invention and Development, Longmans Green and Co, London, 1915
King James W. The Development of Electrical Technology in the 19th Century,: The Telegraph and the Telephone (paper) in Contributions From The Museum Of History And Technolgy, United States National Museum, Bulletin 228, Smithsonian Institute, Washington, 1962, pp 273-332
Lockwood T. D. Practical Information For Telephonists, 1stEdition, W J Johnstone, New York, 1882
Meyer, Ralph O. Old Time Telephones: Technology, Restoration and Repair, Tab Books, New York, 1995
Miller, Kempster B. American Telephone Practice, 3rd Edition, rev. and enlarged . American Electrician Co., New York, 1900
Mountjoy, Richard 100 Years of Bell Telephones, Schiffer, Atglen 1995
Preece W. H. and Maier J. The Telephone, Whittaker, London 1888
Prescott George B. Bell's Electric Speaking Telephone: Its Invention, Construction, Application Modification and History, D Appleton, New York, 1884

Prescott George B. The Speaking Telephone: Electric Light and Other Recent Electrical Inventions, E & F. N. Spon, London, 1879
Rhodes F. L. Beginnings of Telephony, Harpers, New York, 1929
Thompson Silvanus P. Phillip Reis: Inventor of the Telephone, E & F. N. Spon, New York, 1883
Urbanitzky Alfred Ritter, Von The Telephone translated by R Walmsley, in Electricity In The Service Of Man, Cassell, London, 1890
Wiles Frederic Emile Berliner: Maker of the Microphone, Bobbs-Merrill, Indianapolis, 1926
Web Site for Francis Blake, http://www.techantiques.com/blake_home_page.htm

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