Christiaan Huygens – A family affair - Proeven van Vroeger

that he had no new observations yet and to ask whether he had discovered anything new on
the making of telescopes of interest to them. 341 When his brother was in London in April 1661,
Constantijn Jr. wrote him that he made observations of Jupiter with his own telescope and
that he had just sent Christiaan’s Lunettes to him. 342 In December 1663, with Christiaan’s name
climbing to great heights, the demands for staying in the “telescope-race” were increasing.
Constantijn Jr. wrote to his brother on the latter’s plans to devise a longer telescope:
[y]ou talk to me about Telescopes of 55 feet as if it were nothing. If they are of a good
proportion they might bring about great effects. Let me know a little bit of what you discover
with them more than with ours and, in a few words what form they have to grind and polish. 343
Christiaan showed active consideration of his older brother’s opinion in these matters, even
when he already was a member of the Académie des Sciences. 344
In fact, all three brothers and father Huygens were actively involved at several stages
and elements of the production and distribution of the many instruments that Christiaan
worked on. All three were constantly kept informed of the novelties, adjustments and
improvements of instruments, were in contact with the different instrument-makers that
worked on the instruments, and sent or took the instruments all over Europe.
For instance, in Christiaan’s active correspondence with his brother Lodewijk he
regularly discussed the telescope, 345 and there is ample evidence that Constantijn Sr. was
involved in the strategies of distribution and the business of production. When Christiaan
complained to Lodewijk about the costs of the different telescopes that he was obligated to
donate (rather than keeping or selling them) to the highest aristocracy he did not have to
bother about the extra difficulty of the act of giving them to the sovereigns – this was
something his father did. Constantijn Sr. had sent one of Christiaan’s telescopes to the King of
341 HUYGENS, C. (1888) OC., Vol. I, No. 233, 234
342 Ibid., Vol. III, No. 856 Constantijn Jr. to Christiaan Jr. (Apr. 28, 1661)
343 Ibid., Vol. IV, No. 1177 – Constantijn Jr. to Christiaan Jr. (Dec. 6, 1663): “[v]ous me parlez de
Lunettes de 55 pieds comme si ce n’estoit rien. Si elles sont bonnes a proportion elles devroyent faire de
grands effets. Mandez moy un peu ce que l’on en decouvre de plus que par les nostres et en peu de mots
quelle forme de doucir et de polir ils ont.” My translation. Earlier during Christiaan’s stay, Constantijn
Jr. asked his brother information on the making of the telescope in order to be able to proceed: Vol. IV,
No. 1107 – Constantijn Jr. to Christiaan Jr. (Apr. 12, 1663).
344 Ibid., Vol. VI, No. 1576 (Feb. 11, 1667)
345 Ibid., Vol. IV, No. 996 (Mar. 15, 1662); No. 1067 (Oct. 5, 1662); No. 1576 (Feb. 11, 1667); No. 999
(Mar. 29, 1662) Christiaan to Lodewijk : “car il est necessaire que ces lunettes à miroir soient appuiees
par devant a fin de ne point bransler. Et pour cette consideration je croy qu’il vaudroit encore mieux de
la faire de la grandeur qu’est celle du Roy”.
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