72 BELL. 



difference is too small for even its sign to be distinguished with 

 certainty. It is the irony of time that the Cassegrainian form is the 

 one which has survived in the greatest instruments of the present time. 



The writer is glad to be able to drag "Cassegrain, a Frenchman," 

 from something of the obscurity in which he has been veiled, intro- 

 ducing then, Sieur Guillaume Cassegrain, sculptor in the service of his 

 glorious Majesty Louis Quatorze, modeller and founder of statues for 

 the decoration of the king's gardens at Versailles. 



In 1666 he cast a bust of the King, after Bertin's model, for which he 

 received 1200 livres, and for the next twenty years or thereabouts 

 made also many replicas from the antique, including groups like the 

 Laocoon receiving payments from the Royal Treasury for his artistic 

 services well into the year 1684, at which time we lose sight of him. 

 He is believed to have died in the period between 16S4 and 1686. 

 Cassegrain like his friend DeBerce was of Chartres, a city long con- 

 secrated to the art of sculpture. At about the same time that 

 DeBerce sent to the Academy of Sciences the little note on Casse- 

 grain's telescope, Cassegrain himself wrote a long letter to the Academy 

 concerning the speaking trumpet lately invented by Sir Samuel 

 Morland. 



It was in this letter that the writer got the first clew to Cassegrain's 

 identity, since in it he displays beautiful draughtsmanship, as shown in 

 the accompanying copper plate, in striking contrast with his friend's 

 rough sketch, and also a notable familiarity with the art of bell found- 

 ing, which very likely may have been practiced in his own atelier. In 

 fact he. writes like an educated and experienced artist, and was obvi- 

 ously regarded as a person of some consequence, for this letter formed 

 the piece de resistance at the meeting of the Academy of Sciences on 

 the 2nd of May 1672. When and where Cassegrain was born one can- 

 not tell with any certainty, although it is not unlikely to have been 

 somewhere about 1630 to 1635, quite possibly in Chartres. At all 

 events his profession and facilities were such as would very readily 

 have led him toward a reflecting telescope if a hint of Mersenne's sug- 

 gestion to Descartes, or of James Gregory's theory, had come to his 

 notice. 



Note that in the account of Newton's telescope in the Journal de 

 S9avans the word is used in its modern English sense instead of being, 

 as now, confined in French to reflectors, while the Cassegrainian 

 instrument is spoken of as a little "lunette d'approche." One does 

 not generally suggest dimensions for a thing non-existent. Whether 

 Cassegrain actually made and experimented with telescopes nobody 



