84 Mechanical Philosophy, [Chap. L 



artists. The happy efTects of these discoveries and 

 improvements in aiding navigation, and, of course, 

 their favourable influence on commerce and the 

 interests of humanity, are so obvious as not to re- 

 quire formal explanation. 



But no age, assuredly, can vie with the last, in 

 the accuracy and astonishing powers of the astro- 

 nomical instruments which it produced. The prin- 

 cipal ones, among those of an optical kind, were 

 mentioned in a former part of this chapter, and 

 need not be again recounted. In addition to these, 

 many curious instruments and machineSy serving to 

 ilhistrate and exemplify the principles of astro- 

 nomy, have been devised by several ingenious men. 

 The first deserving of notice is the Orrery y invent- 

 ed by Mr. George Graham, an English mathemati- 

 cal-instrument-maker, and presented to George I*. 

 The next is a machine, under the same name, con- 

 trived by Mr. James Ferguson, also of England, 

 and inckiding some improvements on the fonmer. 

 To tJiese succeeded a Plaiietainum, of very curious 

 structure, by Mr. William Jones, of London, and 

 the celebrated astronomical Sphere^ by Dr. Long, 

 professor in the university of Cambridge; to say 

 nothing of a multitude of other inventions of a 

 similar kind, by diflerent artists and astronomers. 



* Thf origin of the name given to this machine is as follows. 

 Mr. llov.lcy^ a iiiatliematical-instrarnent-maker, having obtained 

 one from Graham, the inventor, to be sent abroad, with some of 

 his own instruments, he copied it, and made one for the Eari of 

 Orrtry. Sir Richard Steele, who l^ncw nothing of Mr. Graham's 

 right to the invention, thinking to compliment the noble encou* 

 ragcr, called it an Orrcr>/, and .gave Rowley the praise due t^ 

 Graiiam. 



