The Earth Inductor can be used in the Vertical and Horizontal Plane for the Determination of either "H" or "V". Also widely used for determination of the Earths Angle of Dip. The video maybe of interest, relating to this item. Earth inductor: Coil spun in Earth's field makes voltage.The'Earth Inductor' is a simple generator, illustrating the principle that a changing magnetic field cutting across a loop of wire induces an electric current. In this case, the magnetic field is that of the earth. A coil of wire is rotated in the earth's magnetic field, generating an emf. A simple magnetized needle on a stand finds north. Both the dip-needle and inductor apparatus are aligned with north. The dip-needle indicates the angle of the magnetic flux coming up through the earth. The inductor apparatus frame is tilted so that the coil-frame is perpendicular to the Earth's magnetic flux. The frame is rotated from the horizontal by an angle equal to the compliment of the dip-needle angle. When the coil is rotated, maximum emf is generated at'A' and min is at'B' (in the side-view drawing). The apparatus has commutators so that either an AC sinusoidal signal or DC rectified signal can be amplified and visually represented by the projection galvonometer.
In 1828 the firm was located at 64 Hutcheson and listed as Griffin, Richard & Co. Booksellers and Publishers, Public Library and Newsroom.
In 1832 Richard Griffin died and John Joseph took over running the business. Richard's son Charles at the age of twelve began to assist John Griffin.In the same year John married Mary Ann Holder, by whom he had twelve children. In 1834 John Joseph with his natural attraction to chemistry devoted great efforts to popularizing the study of chemistry. He wrote then published his own book, Chemical Recreations: a popular manual of experimental chemistry. Shortly after the announcement by Daguerre in 1839, the House of Griffin began servicing the needs of Daguerreotypist with chemicals, apparatus and supplies. The book publishing arm allowed Griffin to include his photographic catalogues as an appendix to his published books. Griffin trade catalog was included in the firms famous Encyclopedia Metropolitana as part of Robert Hunts early Manual of photography. Founded the "Chemical Society" with headquarters in London.
The Society was incorporated by Royal charter in the year 1848. In 1842, with Charles having grown up and capable of running the publishing business, John and Charles divided the partnership. John established the scientific instrument and the chemical business as a separate institution and moved it to London, settling down at 53 Baker Street, postman square and appropriately naming the new firm John J.The publishing branch remaining in Glasgow continued as Richard Griffin & Co. In 1848, the two firms resolved to transfer its center to London, but the association with the City of Glasgow and university remained strong. In 1852, John Joseph and his nephew Charles dissolved their partnership with the uncle retaining the London based scientific instrument-making and chemical part of the firm.
Charles Griffin became sole director of one of the most successful and influential publishing houses of the era. From this time the firm carried the name of Charles Griffin & Co. In 1860, John Joseph Griffin publishes his own book, Chemical Reactions: A Popular Manual of Experiemtnal Chemistry. In approximately 1861 John Giffin partnered with Bohn and formed Griffen, Bohn & Co. In 1862 Charles Griffin died and the publishing business left in trust was taken over by his wife Elizabeth Eves Griffin, who developed a remarkable ability to manage the publishing business, assisted by her brothers.
In 1877 on June 9th, John Joseph Griffin Died. His operations at 22 Garrick Street, Covent Garden W. In 1898 the firm introduced to the European market a novel developing paper called Velox. Velox was the first photographic paper that could be printed in artificial light or as Eastman coined it the first of the true gaslight papers ideally suited for amateurs. Four types were made, including "carbon Velox" for matt finish surface, Glossy Velox for an enameled surface, Special Glossy for soft effects, and Rough Velox for naturalistic effects.
The process involved very slow developing of silver chloride contact print paper, much slower than Bromide, and therefore did not require a dark room or colored glass. Also in the same year the firm opened a new factory on Sardina street, just off of Lincoln's Inn Fields. At the turn of the century, the firm advertised a unique new camera line called the Pocket Cyko, meant to mean easy. The two models produced are believed to be of Griffin design that featured a unique construction entirely made of aluminum, which the folded into a flat box for portability. In 1921, John Ross Griffin who was the grandson of John Joseph died.
He was connected with the company until his death. The "House of Griffin" was pioneer photographic supply house, in addition to a significant book publisher.
The item "Antique, Earth Inductor, J Griffin and Sons Ltd London, science / physics" is in sale since Wednesday, February 24, 2021. This item is in the category "Antiques\Science/Medicine\Scientific Instruments". The seller is "andrew_frost7r3b" and is located in Matlock.
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