Fr.: réfracteur de Fraunhofer
The first modern refracting telescope which had an outstanding quality. It was built in 1824 by Fraunhofer for the Russian Imperial Observatory in Dorpat, now Tartu in Estonia. It had a 23-cm → achromatic lens and a German-type → equatorial mounting driven by a clockwork. Wilhelm Struve (1793-1864) used the refractor to observe many → visual binaries, and attempted to measure the distances of stars through their visual → parallaxes. He also obtaibned accurate values for the diameters of the → Galilean satellites of → Jupiter.
Named after Joseph von Fraunhofer (1787-1826), German optician and physicist; → refractor.
Same as → refracting telescope.
Agent noun of refract, → refraction.
From refract, → refraction + adj. suffix -ory.
Sarkeš "refractory, disobedient, rebellious, stubborn,"
literally "withdrw, remove head," from sar
"head" (variants soru, sorun "horn,"
karnâ "a trumpet-like wind instrument," variant sornâ "a wind instrument;"
Mid.Pers. sar "head," sru "horn;" Av. sarah- "head,"
srū- "horn, nail;" cf. Skt. śiras- "head, chief;"
Gk. kara "head," karena "head, top," keras "horn;"
L. cornu "horn," cerebrum "brain;"
P.Gmc. *khurnaz (Ger. Horn, Du. horen;
cognate with E. horn, as above, from PIE *ker- "head, horn;"
O.E. horn "horn of an animal," also "wind instrument;"
E. horn); PIE base *ker-
"head, horn, top, summit")
+ keš present stem of kešidan, kašidan
"to draw; withdraw, remove" (dialectal Yaqnavi xaš "to draw," Qomi xaš
"streak, stria, mark," Lori kerr "line;"
Av. karš- "to draw; to plow," karša-
"furrow;" Proto-Iranian *kerš-/*xrah- "to draw, plow;"
cf. Skt. kars-, kársati "to pull, drag, plow;"
Gk. pelo, pelomai "to move, to bustle;" PIE base kwels-
Fr.: réfracteur de Yerkes
The largest → refracting telescope and the last of the great refractors with a lens diameter of 102 cm (f/d = 19), completed in 1897. The lens was ground by American telescope builders Alvan Clark & Sons. Used mainly for both visual and photographic studies of double stars, it is typical of the long-tube refractors traditionally employed in such work.
After Yerkes Observatory; → refractor.