Celestial Objects for Common TelescopesLongmans, Green, 1873 - 343 páginas |
Dentro del libro
Resultados 1-5 de 48
Página 5
... distance from the glass or mirror which forms it , the power of the same eye - piece in different telescopes varies with the focal length . Hence one disadvantage of a short telescope ; to get high powers , we must employ minute and ...
... distance from the glass or mirror which forms it , the power of the same eye - piece in different telescopes varies with the focal length . Hence one disadvantage of a short telescope ; to get high powers , we must employ minute and ...
Página 6
... distance ( for low powers , a brick wall will answer ) with one eye through the telescope , and with the other alongside of it , and noting how many unmagnified divi- These figures are not , however , always to be depended upon , and ...
... distance ( for low powers , a brick wall will answer ) with one eye through the telescope , and with the other alongside of it , and noting how many unmagnified divi- These figures are not , however , always to be depended upon , and ...
Página 7
... distance between their centres . This value practically concurs with those given by Dallmeyer and Alvan Clark . Reflectors some- what surpass achromatics in this respect , as theoretically they ought to do but they are apt to be more ...
... distance between their centres . This value practically concurs with those given by Dallmeyer and Alvan Clark . Reflectors some- what surpass achromatics in this respect , as theoretically they ought to do but they are apt to be more ...
Página 9
... distance dependent on the duration of the process . An observatory is by no means essential , but it would be difficult to over - estimate its advantage in point of comfort as well as economy of time . It used to be an expensive luxury ...
... distance dependent on the duration of the process . An observatory is by no means essential , but it would be difficult to over - estimate its advantage in point of comfort as well as economy of time . It used to be an expensive luxury ...
Página 22
... distance as to size ; any spots then visible will be easily and , with due precaution , very fairly seen . And so will specks of dirt in the eye - piece ; but these may be detected by moving the tube , as the true spots alone will keep ...
... distance as to size ; any spots then visible will be easily and , with due precaution , very fairly seen . And so will specks of dirt in the eye - piece ; but these may be detected by moving the tube , as the true spots alone will keep ...
Otras ediciones - Ver todas
Términos y frases comunes
achr achromatic aperture Aquil astronomers atmosphere beautiful Binary bluish Boöt bright brighter brilliant Buffham Cassini centre Ceph Clusters colour comet constellation craters curious dark Dawes deep diameter disc Double Stars Drac dusky Earth eye-piece faint field flushed white globe greenish grey Herc Herschel Huggins interior Jupiter larger Lassell libration light lilac limb luminous lunar minute stars Moon motion naked eye nearly nebulæ noticed nucleus object object-glass observers orange pair pale blue pale white pale yellow photosphere Pisc planet proper motion Red Star reflector region remarkable Right Ascension ring ruddy satellites Schm Schr Schröter Schwabe Secchi seen shadow shew side silvery white smaller smalt solar sometimes spec spots streaks surface Taur telescope topaz Triple Virg visible xIxh xvih XVIII yellowish
Pasajes populares
Página 345 - A NEW STAR ATLAS, for the Library, the School, and the Observatory, in Twelve Circular Maps (with Two Index Plates). Intended as a Companion to ' Webb's Celestial Objects for Common Telescopes.
Página 46 - Fairest of stars, last in the train of night, If better thou belong not to the dawn, Sure pledge of day, that crown'st the smiling morn With thy bright circlet, praise Him in thy sphere, While day arises, that sweet hour of prime.
Página 182 - Lift up your eyes on high, and behold who hath created these things, that bringeth out their host by number; he calleth them all by names by the greatness of his might, for that he is strong in power; not one faileth.
Página 345 - Why didn't somebody teach me the constellations, too, and make me at home in the starry heavens which are always overhead, and which I don't half know to this day?
Página 30 - I have said, he spent to satisfy himself; six more years to satisfy, and still thirteen more to convince, mankind. For thirty years never has the Sun exhibited his disc above the horizon of Dessau without being confronted by Schwabe's imperturbable telescope, and that appears to have happened, on an average, about 300 days a year.
Página 65 - Webb makes the following remarks on the rills:—"These most singular furrows pass chiefly through levels, intersect craters (proving a more recent date), reappear beyond obstructing mountains, as though carried through by a tunnel, and commence and terminate with little reference to any conspicuous feature of the neighbourhood.