AS LECTURED UPON BY HIS SON,
W. WALKER.
THE FOURTEENTH EDITION.
Ipswich;
PRINTED FOR THE AUTHOR,
BY BURRELL AND BRANSBY;
AND SOLD BY J. ROBSON AND W. CLARKE, BOND-STREET;
AND G. KEARSLEY, FLEET-STREET, LONDON.
1800.
This elaborate Machine is 20 feet diameter:it stands vertical before the spectators;and its globes are so large, that theyare distinctly seen in the most distant part ofa Theatre. Every Planet and Satellite seemssuspended in space, without any support;performing its annual and diurnal revolutionswithout any apparent cause. It is certainlythe nearest approach to the magnificentsimplicity of nature, and to its just proportions,as to magnitude and motion, of anyOrrery yet made: and besides being a most[2]brilliant and beautiful spectacle, conveys tothe mind the most sublime instruction: renderingastronomical truths so plain and intelligible,that even those who have not so muchas thought upon the subject, may acquireclear ideas of the laws, motions, appearances,eclipses, transits, influences, &c. of the planetarysystem.
THE SUN AND EARTH:
With the Zodiacal Constellations.
As information is the primary object of thislecture, it is thought more useful to exhibitparts of the solar system, separately, beforea grand display was made of the whole. Thisscene therefore, opens with only the Sun andthe Earth. The Sun seems suspended in themiddle of the system, and by spots on his[3]face, is seen to turn round on his axis in 25¼days; light issues from his orb in all directions;in the blaze of which is suspended theEarth, turning on its axis to produce day andnight, and revolving round the Sun to producethe seasons: its axis inclines 23½ degreesfrom a perpendicular to the plane of itsorbit; and by that axis keeping parallel toitself during this annual journey, the northernand southern hemispheres are alternately addressedto the Sun; shewing, when it is summerin one, it is winter in the other, and viceversâ. This scene so naturally exhibits thecause of day, night, twilight, summer andwinter, spring and autumn, long and shortdays, &c. that a bare inspection of the Machineis sufficient to convey the clearest ideaof these phænomena.
The Earth in this scene ought to be unshackledwith meridians or pa