Dividing engine at the Museo Galileo in Florence. There has always been a need for accurate measuring instruments. Whether it is a linear device such as a ruler or vernier or a circular device such as a protractor , astrolabe , sextant , theodolite , or setting circles for astronomical telescopes , the desire for ever greater precision has always existed. For every improvement in the measuring instruments, such as better alidades or the introduction of telescopic sights, the need for more exact graduations immediately followed. In early instruments, graduations were typically etched or scribed lines in wood , ivory or brass. Instrument makers devised various devices to perform such tasks.
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The family were not well off and Jesse attended a free school in Halifax from to At this stage Ramsden was sent to live with his uncle, Mr Craven, in the North Riding of Yorkshire, and he spent four years there studying mathematics taught by the Revd Mr Hall. Around he was apprenticed to a cloth maker, and he spent until serving his apprenticeship.
He went to London at this stage and was given a job as a clerk in a cloth warehouse but, in at the age of 21, he chose to become an apprentice to Mark Burton, a mathematical instrument maker in Denmark Street in the Strand. By the age of 27 he had his own business in London in the Strand where he became acknowledged as the most skilful designer of mathematical, astronomical, surveying and navigational instruments in the 18th century.
A near neighbour was John Dollond, a fellow of the Royal Society and a skilled designer of optical instruments. Of their two sons and two daughters, only one son, John Ramsden, survived to adulthood. Marriage gave Ramsden a share in the patent that John Dollond had taken out on his most famous invention, the achromatic lens. Ramsden soon opened a new business in Haymarket, near Little Suffolk Street. The French scientist N Cassegrain proposed a design of a reflecting telescope in It was Ramsden, however, years later who found that this design reduces blurring of the image caused by the sphericity of the lenses or mirrors.
Optical instruments at this time were important for a number of reasons, but the big problem of the day which many scientists attacked, was solving the problem of computing longitude at sea.
Maskelyne had also compiled lunar tables but accurate instruments were needed to be able to take bearings from ships before they were useful. Ramsden produced such an instrument in but it did not give as accurate results as was hoped. Although he was highly successful in his business, Ramsden does not appear to have been so successful with his marriage for his wife did not move with him when he opened larger premises in Sarah and their son John moved into a house owned by the Dollond family, but Sarah seems to have continued to assist Ramsden in his business.
Indeed Ramsden continued to expand his business, enlarging his premises in His also continued to devise important new inventions, one of these being the circular dividing engine.
This allowed for the mass production of instruments such as sextants, for the dividing engine provided mechanical graduation of scales. Particular emphasis is given to the invention, evolution and transmission of the methods used to achieve accuracy in dividing the wheel, ratcheting the teeth and matching them to the endless screw, and mounting the cutter.
The procedures adopted by Ramsden and Troughton for correcting initial dividing marks are also described. Ramsden was elected fellow of the Royal Society on 12 January and received the Copley Medal in for He was elected to the St Petersburg Academy of Sciences in He was His countenance was a faithful index of his mind, full of intelligence and sweetness.
His forehead was open, and high, with a very projecting and expressive brow. His eyes were dark hazel, sparkling with animation. He had a good musical voice. This quote was by the Revd Louis Dutens who also said that Ramsden [ 2 ] Several of his apprentices went on to distinguished careers in their own right This did not happen and Ramsden died there.
The following article by Anthony A. This wonderful machine is on exhibit at the Museum of Surveying in Lansing, Michigan In , Jesse Ramsden of England invented the circular dividing engine, an instrument which had a profound impact on Western history. Prior to his invention, the division and inscription of scales on mathematical instruments was done by hand. Therefore, the value of the instrument depended on the accuracy of the maker and his tools. Instruments such as surveying compasses were subject to wide variations in quality, as each instrument required a maker with an extraordinary control of tools and a very precise eye. Instruments were produced one at a time, which limited the number available for purchase and making them prohibitively expensive.
Ramsden Dividing Engine
The family were not well off and Jesse attended a free school in Halifax from to At this stage Ramsden was sent to live with his uncle, Mr Craven, in the North Riding of Yorkshire, and he spent four years there studying mathematics taught by the Revd Mr Hall. Around he was apprenticed to a cloth maker, and he spent until serving his apprenticeship. He went to London at this stage and was given a job as a clerk in a cloth warehouse but, in at the age of 21, he chose to become an apprentice to Mark Burton, a mathematical instrument maker in Denmark Street in the Strand.