This chronometer incorporates the very rare Dent's registered prismatic compensation balance type "B" as improved by Frederick Rippon in 1852.This balance corrects the secondary error without any secondary mechanical contrivance, and does not increase the expense, whilst its prismatic figure adds great strength to the balance rim, rendering the chronometer far less liable to injury from transit, and its performance more uniform.Dent's superior marine chronometers, fitted with the prismatic balance were retailed at the price of 40 Guineas each.On November 10, 1851, Dent wrote from 61 Strand to Airy to ask his opinion on a plan which he thinks might have the effect of correcting the want of agreement between the inertia of the balance and the varying elastic force of the balance spring in a chronometer, in order to get rid of the secondary compensation which at all times is objectionable. The plan suggested for experiment was to alter the shape of the steel in the balance spring from that of cylindrical form and having the steel and brss of the same figure, and is, to make the steel of an angular (or prism) shape Type "A". He thought then there will be resistance from the steel ring of this shape to prevent the brass, by his construction, from carrying out the rim so far by a decrease of temperature, and the reverse on an increase.In his reply the following day, Airy believes that the construction proposed for the balance would produce no particular effect different from that of the common construction, but he would not profess to give this as an opinion deserving any attention. He suggested to make the experiment which should not be difficult.A month later, once the first experiments were made, Dent wrote to Airy, to inform him that the prismatic balance had been tried from 110° to below 17° and at all the intermediate temperatures and that never before he had observed a rate so uniform in any other balance.A second type "B", improved by Frederick Rippon in 1852, was composed of a prismatic shaped piece of steel, having the brass likewise prismatic in section.A third type "C" was produced by Frederick Dent in about 1853, which was a flat piece of steel with an outer prismatic shaped piece of brass. This was in fact a simplified form which was much easier to produce.Richard Rippon. Marianna Frederica Dent, née Cowslade, married Richard Rippon on 15 October 1850 who had assumed shortly before the name of Dent, that of his father-in-law. The couple were responsible for the branch of the Dent business at 33 Cockspur Street which became their outright property on the death of E. J. Dent in 1857. Following the death of her husband in 1857, Marianna Frederica continued the business under her own name, although she re-married in 1860 with Samuel Ward Fuller. in 182 M. F. Dent showed a selection of watches at the international Exhibition and again at the Paris Exhibition of 1867. On 14 October 1869 Marianna Frederica died of a liver disease.