A direct current generator patent model. US Patent 233942, Dynamo Electric Machine, issued 2 November 1880 to Hiram S. Maxim. Claims: Improvement of ventilation within the armature to reduce heating; easily replaceable commutator. Machine has two flat field coils at top and bottom, painted red. Large armature wound with blue wire rotates in the field. Pulley is attached to one end of the armature shaft, commutator with brushes at the other end. Schroeder, History of the Electric Light, page 41.
Telegraph keys are electrical on-off switches used to send messages in Morse code. The message travels as a series of electrical pulses through a wire. The operator pushes the key’s lever down briefly to make a short signal, a dot, or holds the lever down for a moment to make a slightly longer signal, a dash. The sequence of dots and dashes represent letters and numbers. This key was received disassembled and has a switch on the side called a circuit-closer that takes the key off-line when not in use.
Invention rarely stops when the inventor introduces a new device. Thomas A. Edison and his team worked to improve his electric lighting system for some years after the initial introduction in 1880. This lamp shows changes made after about ten years of labor aimed at lowering costs and increasing production. The simplified base required little material; the diameter and thread-pitch are still used today. The filament was changed from bamboo to a treated cellulose, based on an invention by English chemist Joseph Swan. The bulb was probably free blown by Corning Glass Works, but would soon be replaced by a bulb made by semi-skilled laborers blowing glass into iron molds. The cost had dropped from about $1.00 per lamp to less than 30¢.
This ammeter consists of a brass current carrying conductor and indicating mechanism mounted on a wooden base. Case missing. Marked: "Current Indicator #2243 Cap. 500 amperes Pat. Oct. 22, 1889, Mfg. by Thomson-Houston Electric Co., Lynn, Mass. U.S.A." The current to be measured passes through a single turn conductor in which is pivoted eccentrically a soft iron movement controlled by gravity. As a result of the eccentricity the current tends to rotate the iron piece into a position nearer to the conductor, causing a scale deflection as a measure of the current. In all meters of this type it is necessary to bring the entire current to be measured to the switchboard and in to the instrument. This necessity was eliminated by the invention of Dr. Edward Weston of the permanent magnet movable coil type of instrument incorporating a heavy current shunt.
Solar power starts with the sun. This color lithograph is one of a set produced by Étienne L. Trouvelot (1827-1895) and published by Charles Scribner's Sons in 1881. “Solar Protuberances” is based on observations of the sun Trouvelot made on 5 May 1873. This particular lithograph was one of several used by traveling science lecturer Charles Came and later by his son-in-law Samuel Corby during public presentations given in the latter nineteenth century.
Electricity pioneer Lewis Latimer drew this component of an arc lamp, an early type of electric light, for the U.S. Electric Lighting Company in 1880.
The son of escaped slaves and a Civil War veteran at age sixteen, Latimer trained himself as a draftsman. His technical and artistic skills earned him jobs with Alexander Graham Bell and Thomas Edison, among others. An inventor in his own right, Latimer received numerous patents and was a renowned industry expert on incandescent lighting.