March io, 1892] 



NATURE 



435 



-October. A similar article of attire, despatched by him 

 to the Hague for his elder brother's wear, figures in 

 several letters, and engaged many anxious thoughts ; 

 but a little plot concocted by the par nobile fratrum for 

 extracting the price — amounting to four and a half louis — 

 from the liberality of their father, the Secretary, appears 

 to have been baffled. They were, indeed, often made to 

 feel— though not with any unreasonable harshness— that 

 he who keeps the purse holds the reins ; for the paternal 

 authority exercised in their family was of no shadowy 

 kind. The elder Constantine ordered his three sons- 

 middle-aged, in Dante's sense, though they were — from 

 realm to realm at his good pleasure, and was obeyed with- 

 out hesitation. And notwithstanding that his demands 

 from Paris for optical toys— pocket-telescopes, magic- 

 lanterns, and the like— gave Christian considerable 

 annoyance, he did not venture to refuse, or so much as 

 remonstrate against the fulfilment of paltry, troublesome, 

 and, to his sentiment, humiliating commissions. He, 

 however, stooped instead to the scarcely laudable sub- 

 terfuge of begging his brother Louis, then in Paris, to 

 abstract one of the three lenses of the lantern, and so 

 bring about at least a postponement of his father's ap- 

 pearance at the Louvre in the character of showman 

 to scientific " marionettes," no longer claiming even the 

 distinction of. novelty. 



Huygens spent the whole of 1662 in Holland, occupied 

 mainly with experiments on the "weight and spring of 

 the air." Pneumatic inquiries just then, largely through 

 Boyle's example, raised very general curiosity ; and pneu- 

 matic engines attracted much constructive ingenuity. 

 The mode of creating vacua had been recently arrived 

 at ; phenomena of an unforeseen kind thence ensued, 

 and led to continual surprises ; their investigation in- 

 volved that of the qualities and functions of the air ; 

 upon which the learned, accordingly, promptly and 

 eagerly entered. Huygens among the number ; yet with 

 no result of the first order of importance. He fabricated 

 an improved air-pump ; and observed by its means some 

 apparently anomalous effects, which occupied many of his 

 thoughts, and gave rise to an extensive correspondence, 

 both with French savants, and with Sir Robert Moray as 

 the representative of the Royal Society of London. They 

 did not, however, prove to possess all the significance 

 which he was at first disposed to attach to them. Less 

 than his customary success, also, about this time attended 

 his efforts to give to pendulum-clocks the perfection 

 needed for the solution of the problem of longitudes. 

 His coadjutor was the ingenious Alexander Bruce, a few 

 months later Earl of Kincardine, who, with unlucky re- 

 sult, took a pair of the carefully-adjusted timepieces on 

 a trial voyage from the Hague to London in December 

 1662. The sea was rough; the ship a small one, but 

 with large capacities for rolling and pitching ; whereby a 

 test more searching than tolerable was applied to the 

 novel mechanism. One clock, thus " furiously shaken," 

 lost the bob of its pendulum ; the other stopped, and 

 their custodian, having succumbed to sea-sickness, could 

 do next to nothing to remedy the damage. Evidently, the 

 purpose in view demanded some better invention, such as, 

 indeed, Robert Hooke had already hit off, but, after his 

 usual volatile fashion, had thrown, still incomplete, aside. 

 On arriving in Paris, April 3, 1663, the first care of our 

 NO. I 167, VOL. 45] 



mathematician was to have himself bled, in order to get 

 rid the sooner of a cold caught on the journey of six full 

 days from Brussels ; and the operation, singularly enough, 

 produced the intended effect. His next desire was to place 

 himself ate couratit of the state of practical optics in the 

 French capital, and to compare his lenses with those 

 ground and polished by Auzout and D'Espagnet. The 

 handiwork of the latter excited his particular admiration ; 

 but the secret of his methods was carefully guarded, and 

 Huygens records, with a perceptible shade of irritation, 

 the vigilance of the Bordeaux alchemist over a case of 

 lenses which might, for the care bestowed in keeping 

 them tucked under his arm, have been a box-full of 

 pistoles. He found, however, " Messieurs les Lunettiers" 

 less advanced than he had expected in their grand 

 schemes for telescopes 80 and 100 feet in length. 



He set out with his father for London on June 7, and both 

 were present three days later at a meeting of the Royal 

 Society, where they were entertained with "occasional 

 observations," and " promiscuous discourses," relating to 

 petrifactions, the smutting of corn, the amelioration of 

 flowers, and sundry other topics. Christian testified 

 his usual courteous interest in the proceedings ; but ex- 

 pressed, none the less, in one of his confidential letters 

 to his brother Constantine, something of scorn for the 

 miscellaneous doings at Gresham College. And he felt 

 himself, he said, no whit the wiser for his election as a 

 Fellow of the Society on June 17, 1663. English festivi- 

 ties, however, he admitted to be splendid. " This is the 

 true land of good cheer," he wrote, after a succession of 

 dinners given by the Earls of Manchester, Albemarle, 

 and Devonshire, all of which were outdone by the 

 brilliant hospitality at Roehampton of the Dowager 

 Countess of Devonshire. A Court ball evoked no special 

 comment ; and perhaps Huygens's most genuine interest 

 in London was in his visits to Sir Peter Lely's studio. Both 

 he and Constantine dabbled about that period in pastels, 

 and the recipe by which Lely's crayons were fabricated 

 was an object of eager desire to them. It was freely 

 imparted, and is here printed (p. 372). 



Huygens quitted London on October i, and spent the 

 remainder of the year in Paris. And since his movements 

 were regulated, not by the claims of science, but by 

 family arrangements, his letters thence referred to no 

 critical problems of that age. They are accordingly 

 more " readable," in the general sense, than might have 

 been expected from a geometer of his profundity ; those 

 I addressed to his brothers, which form the majority in the 

 present volume, being even playful and diverting. To 

 them he showed himself without disguise. He sent them 

 lively causeries, rather than formal epistles ; social jot- 

 tings, family intelligence, the first hints of his anticipated 

 triumphs, his unvarnished opinions of his contemporaries : 

 they alone were allowed to see that there was a keen edge 

 to his wit. His erudite correspondents on occasions put 

 him fairly out of patience ; yet to Louis Huygens alone 

 was it confided that he thought Chapelain intolerably 

 tedious, and Petit uncommonly dull. Constantine, on 

 the other hand, was the recipient of his impressions 

 touching the harpsichord performance of William Brere- 

 ton, a distinguished member of the Royal Society. Its 

 effect upon a trained musician like Huygens can easily 

 be gathered from the ominous facts that the player was 



