American Bell Tel. Co. v. Spencer

• Decision Date: 27 June 1881
• Citation: 8 F. 509
• Parties: AMERICAN BELL TELEPHONE CO. and others v. SPENCER and others.
• Court: U.S. District Court — District of Massachusetts

8 F. 509

AMERICAN BELL TELEPHONE CO. and others v. SPENCER and others.

United States Circuit Court, D. Massachusetts.

June 27, 1881

J. J Storrow, Chauncy Smith, and E. N. Dickerson, for complainants.

Frederick H. Betts, for defendant.

LOWELL C.J.

The bill alleges an infringement of two patents (No. 174,465 dated March 7, 1876,-- improvement in telegraphy; No 186,787, dated January 30, 1877,--improvement in electric telegraphy) granted to Alexander Graham Bell. The defendants admit that they have infringed some valid claims of the second patent, but the plaintiffs are not content with this admission; they rely, besides upon the fifth claim of the first patent, which is much more comprehensive in its scope.

Patent No. 174,465, issued to Bell, dated March 7, 1876, is entitled 'Improvement in Telegraphy,' and is said in the specification to consist in--

'The employment of a vibratory or undulatory current of electricity, in contradistinction to a merely intermittent or pulsatory current, and of a method of and apparatus for producing electrical undulations upon the line wire.'

The patentee mentions several advantages which may be derived by the use of this undulatory current, instead of the intermittent current, which continually makes and breaks contract, in its application to multiple telegraphy; that is, sending several messages, or strains of music, at once over the same wire, and the possibility of conveying sounds other than musical notes. This latter application is not the most prominent in the specification; though, as often happens, it has proved to be of surpassing value. This part of the invention is shown in figure 7 of the drawings, and is thus described in the text:

'The armature, c, figure 7, is fastened loosely by one extremity to the uncovered leg, d, of the electro-magnet, b, and its other extremity is attached to the center of a stretched membrane, a. A cone, A, is used to convey sound vibrations upon the membrane. When a sound is uttered in the cone, the membrane, a, is set in vibration; the armature, c, is forced to partake of the motion; and thus electrical undulations are created upon the circuit E, b, e, f, g. These undulations are similar in form to the air vibrations caused by the sound; that is, they are represented graphically by similar curves. The undulatory current passing through the electro-magnet, f, influences its armature, h, to copy the motions of the armature, c. A similar sound to that uttered in A, is then heard to proceed from L.'

With the figure 7 before us, this description is readily understood. A cone of pasteboard, or other suitable material, has a membrane stretched over its smaller end; at a little distance is a piece of iron magnetized by a coil through which is passing a current of electricity. When sounds are made at the mouth of cone, A, the membrane vibrates like the drum of a human ear; and the armature, which is directly front of the magnet, vibrates with the membrane, and its movements cause pulsations of electricity, like those of the air which excited the membrane, to pass over the wire; and the wire stretches to another similar magnet and cone with its membrane and armature. The second armature and membrane take up the vibrations and make them audible by repeating them into the condensing cone, L, which translates them into vibrations of the air.

The defendants insist that the instrument represented in figure 7 will not transmit articulate speech; that this great result has been reached by Mr. Bell entirely through the improvements described in his second patent, such as the substitution of a metal plate for the stretched membrane, and some others.

The...