On 26 December 1657 Christiaan Huygens (1629-1695) writes to the French astronomer Ismael Boulliau (1605-1694) that he had made his first pendulum clock “yesterday just a year ago”, and that since June he had been showing the construction to everybody interested. This last remark is related to the fact that on 16 June 1657 Salomon Coster (c. 1620-1659) had obtained the exclusive rights (‘privilege’) for a period of 21 years to make and sell these clocks.
The earliest description by Huygens.
The earliest description by Huygens is in his letter to Jean Chapelain (1594-1674) in Paris, dated 28 March 1658.
Christiaan Huygens (1629-1695)
A drawing explains the principle in Huygens’
letter to Chapelain.
Jean Chapelain (1594-1674)
A drawing explains the principle; in Huygens’ own clock the balance wheel is replaced by a six inch long pendulum suspended from a thread. It seems likely that Huygens is referring here to the timepiece made by Salomon Coster with a pendulum of 13.7 cm, of which five have been preserved. Shortly afterwards, Huygens tries to get his pendulum clock also granted in France. As he fails, he hastens to publish his new invention in “Horologium” (September 1658). In concluding the text, Huygens gives some information on the clocks as designed by Coster:
“I have indeed seen in the workshop of him whose labours I first employed for these constructions completed pendulum clocks which go not by a weight but by the force of a spring. In this kind of work, up to the present time, the differing power of the spring when wound up and when run down was equalised by the aid of a fusee round which was coiled a gut line; now these are disused. For the teeth are brought together with the barrel itself, in which the spring is enclosed. Although it is admitted that by this method the motion of a pendulum is not equally vigorous in the beginning and at the end [of the spring power], nevertheless the effect is not to reduce the time of the concluding oscillations, as has been proved earlier. The manner of adjusting and apportioning the spring-tension, in fact is such that no slight loss in timekeeping occurs during the working of the timepiece. I pass over clocks of this kind which have been contrived to sound the hours by one and the same motor, either a weight or a spring, which serves also for turning the hands of the timepiece, since all these have no connection with my invention.”
We learn from this translation of Huygens’ exposition that the movements by Salomon Coster did not have a fusee and that the production was not restricted to timepieces; Coster made also clocks with an addition striking train driven by the same spring.
Huygens’ letter to Pierre Petit, November 1658.
A letter by Huygens to Pierre Petit (1598-1677), dated 1 November 1658, informs us more closely about his two measures to further the accuracy of the clock. In order to eliminate the effect of the pendulum’s amplitude as much as possible, Huygens introduced curved cheeks which diminish automatically the length of the pendulum for larger amplitudes. The optimal shape of these cheeks he determined experimentally. Shortly after this date (at least prior to 22 January 1660) he deduces mathematically that the ideal cheeks should have the shape of a cycloid, ( ) and for that reason we refer to them as cycloidal cheeks. As a second measure for spring-driven clocks, Huygens indicates that the variations of the spring can be reduced by limiting the number of revolutions of the spring barrel.
This letter presents still more information on Coster’s clocks. Winding the spring directly has the advantage of the going train being permanently under tension, so that the clock will not stop during this operation. Coster provides his domestic clocks with a minute ring around the hour ring. He needs only one extra wheel to show the phases of the moon, the days of the month and of the week. The clocks have a horizontal escape wheel, in this respect deviating from the construction given by Huygens in ‘Horologium’, where he introduced an additional gear to minimise the amplitude of the pendulum not provided with curved cheeks. Coster just informed him that he needed three to four weeks to make a spring-driven clock with striking, price D. fl. 120. The clockmaker made such clocks going for a week on a single spring.
Coster clocks pricelist, January 1659.
In a letter by Huygens to Boulliau dated 16 January 1659 we find a specification of the various clocks deliverable by Coster, including prices:
|Weight||Spring||Striking||30 hr.||8 day||Price|
A Coster clock described in Florence, 1690.
A very important additional source of information on Coster’s clocks is an inventory made up in Florence in 1690. It gives the description of a hanging clock with a short pendulum in an ebony case with a glass front, half an ell high, with a silver chapter ring on velvet and an ornament, also silver, inscribed ‘Salomon Coster’. This clock was sent to the grandduke Fernando II de’ Medici (1610-1670) on 25 September 1657 and indicated as the first pendulum clock arrived in Italy.
This historical survey gives a surprisingly detailed specification of the earliest pendulum clocks made by Salomon Coster: a movement with or without striking, driven by the same barrel, provided with a horizontal escape wheel, with the pendulum suspended on a thread between (more or less cycloidally shaped) cheeks, length about six inches, the dial plate covered with velvet on which a single chapter ring for the hours as well as the minutes and a dito silver cartouche with the name of the maker, all this as a hanging clock in an ebony box with a glass front. It sounds like the des-scription of the clocks which have survived the three and a half centuries since their construction.
Two foreign co-workers.
Salomon Coster could make use of the labour of two foreign co-workers in the few years prior to his early death in December 1659. The more wellknown was John Fromanteel (1638 – prior to 1692), son of Ahasuerus Fromanteel (1607-1693), clockmaker in London. How the news of the new invention reached him is not known. Possibly through John Roussel, born in The Hague in 1633 as the elder son of the clockmaker Cornelius Roussel, originating from London. From 1655 to 1657, this John was apprenticed to a London clockmaker. Both Johns came to The Hague in 1657, both are mentioned as witnesses in a certificate dated 13 October 1657.
On 3 September 1657 Salomon Coster and John Fromanteel signed a deed according to which the latter agreed to make clock movements in Coster’s shop as he had already done before. For each movement he will receive D.fl. 20.- if he uses his own brass and iron, D. fl. 18.50 if these materials are provided by Coster. The fixed unit price indicates that Fromanteel was to make a series of identical movements; it seems evident that the agreement refers to the most simple version of a spring-driven timepiece, price D.fl. 80.-. As John Fromanteel is mentioned in deeds dated February 1659 and October 1660, we may assume that he was working again in The Hague in those years. It is possible that he kept Coster’s workshop going after the latter’s sudden death in December 1659 until it was taken over by Pieter Visbagh (c. 1634-1722) in November 1660.
A second temporary co-worker, also from abroad, is the Paris clockmaker Nicolas Hanet (?-1723). The fact that he is referred to in Huygens’ correspondence as ‘Sieur Hanet’ gives the impression that he was more than just an average artisan. We find Hanet for the first time mentioned anonymously as ‘Coster’s agent’ who worked with him in The Hague, in a letter dated 29 November 1658. It is tempting to suppose that Hanet’s interest had been roused through contacts with the Paris correspondents of Huygens.
From the correspondence we can conclude that Nicolas Hanet visited The Hague at least three times: in September 1658 he returns from his first visit to The Hague, during which he may have worked with Coster, with two or three Coster clocks. These first pendulum clocks in Paris were bought by Louis Charles d’Albert, Duc de Luynes (1620-1690), mentioned as a ‘grand amateur’ of clocks. We hear also that Hanet himself made a pendulum clock in 1658. The second journey to The Hague takes place in February-March 1659, in which case Hanet returns to Paris with four Coster clocks. In December 1659 he travels for the third time to The Hague, apparently for a short visit. As a result of the sudden death of Coster his return is delayed to March/April 1660. This may indicate that Hanet worked in the preceding months in Coster’s shop, possibly finishing clocks designed for Paris clients. In a certificate of 23 December 1659 Claude Pascal authorises Nicolas Hanet to collect 41 pounds in his name. From the correspondence we can conclude that in 1658-1660 at least eleven clocks by Salomon Coster have been brought to Paris, partly by Hanet, partly sent with books of the Leiden publisher Elsevier. Thanks to the letters preserved we are rather well informed about the transactions to Paris, but unfortunately we have no data on clocks made for Dutch clients.
Considering the number of clocks mentioned and the cooperation of John Fromanteel, Nicolas Hanet, as well as the orphan Christiaan Reijnaert (c. 1647-1699), who as a ten year old orphan was apprenticed to Coster in 1657, we may assume that in less than three years Coster’s shop had a large output of pendulum clocks. On the basis of his statement that he needed 3 to 4 weeks to make a clock, it seems reasonable to suppose that in the years 1657-1660 at least 30 to 40 clocks were delivered in and outside the country.
Thanks to the fact that Huygens’ involvement with the ‘export’ of pendulum clocks was continued for some years after Coster’s death, data on the further development have been preserved. His visit to Paris (October 1660 to March 1661) discloses that in the mean time three or four clockmakers in that city are producing pendulum clocks; (Gilles) Martinot (1622-1688) is men¬tioned by name as having been visited by Huygens twice. We can assume that, in addition to Mar¬tinot and Nicolas Hanet, Isaac Thuret (c. 1630-1706) belonged to this group.
Back in The Hague, Huygens receives new requests for clocks to be delivered under his supervision. In a letter from January 1662 Claude Pascal is mentioned for the first time. We know of him only that he originated from France or Geneva, worked in The Hague at least since September 1654 and died shortly after 1670. Apparently in the beginning Huygens was very satisfied with his work, for in the time up to 1664 he employs him six or more times for making clocks ordered from Paris. For five of these clocks Christiaan Huygens himself is a witness of the state in which they arrive. In two cases he criticises the quality of the clocks as being made not as well as his earlier clocks. The other three have suffered so seriously during transport that he calls on Isaac Thuret, whom he may have met through his contacts with the Paris astronomers, to repair the clocks. From the letters of Christiaan Huygens to his brother Constantijn in The Hague we learn that some of these were striking clocks and that the case of one clock was veneered with tortoise shell.
In view of these bad experiences, Huygens decides in April 1664 not to charge himself any more with ordering clocks. Without doubt, this decision was also due to the fact that, as his father Constantijn had already reported during the latter’s visit to Louis XIV in 1661, the Paris clockmakers were making better pendulum clocks than their confreres in The Hague, clocks he prefers to his own ‘Hague’ clock. Christiaan Huygens asks for a description of how the clocks by Thuret are designed but, unfortunately, this description is not preserved. We may assume that his father’s preference concerned primarily the more beautiful finish of the French clocks compared with the sober design of the Coster clocks.