HISTORY OF PHYSICAL ASTRONOMY.

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the sun to be 35"; according to the Connaissance des Temps it amountsto 32".3 *.

It appears from the foregoing statements that Gascoigne invented andactually employed the micrometer twenty years before even the originalgerm of such an instrument had suggested itself to any person on theContinent. At the same time, there is not the smallest reason to supposethat any person out of England had any knowledge of his labours previousto the reinvention of the instrument elsewhere. On this point Delambremakes the following just remark :—“ II faut remarquer que les observa-tions des deux amis nont ete publiees que 80 arts apres leur date reelle.Ainsi, en accordant a Gascoigne , la premiere idee et meme la premiere execu-tion du micrometre, il est juste de reserver leurs droits aux astronomes qui,sans avoir aucune connaissance des observations Anglaises, ont ete conduitspar leur propres reflexions d la meme decouverte.”\

There can be no doubt that the micrometer of Gascoigne and Auzout isimmeasurably superior to any reticule or graduated scale placed in thefocus of the telescope, such as was used by Huyghens and the MarquisMalvasia on the Continent, and by Hooke in England. It is right tohear in mind, however, that both Wren and Hevelius had suggested themeasurement of small angles, and of the fractional parts of large angles,by means of the revolutions of a screw, although it does not appearthat on any occasion they reduced their ideas to practice.

William Gascoigne, the individual just referred to, was the son of HenryGascoigne, Esquire, of Middleton, in Yorkshire . While only eighteenyears of age he appears to have been actively engaged in observing thecelestial bodies, and in advancing the state of optics and practical astro-nomy. He continued to prosecute his labours with remarkable successtill the outbreak of the civil wars in 1643, when he joined the cause ofCharles I. , and fell at the battle of Marston Moor on the 2nd of July,1644, in the twenty-fourth year of his age. To his untimely fate may heapplied the language of a distinguished historian in reference to the accom-plished young statesman who, in the previous year, fell at the battle ofNewbury, fighting in the same cause :—“ II mourut, victime d’un temps troprude pour sa pure et tendre vertu.”\ Richard Townley states that Gas-coigne had a Treatise on Optics just ready for the press, hut that notwith-standing all his efforts he was unable to obtain any trace of it after hisdeath §. Sherburne, in his translation of “ The Sphere of Manilius,” as-serts that Gascoigne was the first person who made a telescope composedof two convex lenses ||. Whether this be true or not, it is very certain,at all events, that he was the first who applied a telescope of such a con-struction, to those purposes for which it is peculiarly designed.

The application of the telescope to divided instruments, so as to servein ascertaining the apparent direction of a celestial body, was another ofthose great improvements which distinguished the progress of practicalastronomy in the seventeenth century. The idea of employing the tele-scope in this manner seems to have first suggested itself to Morin, aFrench astronomer, notorious for his opposition to the Gopernican theoryof the universe, and his devotion to astrological pursuits. In 1635 heascertained the interesting fact, that it was possible to see the stars inthe daytime by the aid of the telescope, and he sought to avail himself of

* Hist. Ast. Mod., tome ii., p. 590. f Ibid.

I Guizot, Histoire de la Revolution d’Angleterre, livre iv.

§ Phil. Trans., 1667, p. 457.

II “ The Sphere of Manilius,” translated into English, p. 92, fol., London , 1675.