of the Heavenly Bodies. 25 



meter, or together with these, inasmuch as the states indicated 

 by these instruments mutually affect each other. In ordinary 

 cases, these instruments may be consulted, but where extra- 

 ordinary accuracy is required in determining the places of the 

 heavenly bodies, recourse must be had to more direct obser- 

 vations made at the time. 



I have thus accounted for the changes of place in the heavenly 

 bodies, the changes of colour, the changes of figure and di- 

 mensions, and the occasional undulatory changes of limb and 

 outline, together with the occasional variations even of these 

 changes, by referring them to the same principles, to one and 

 the same existing cause, acting variously, and variously mo- 

 dified ; and he who can continue to believe that the apparent 

 increase of size of the sun and moon, in the horizon, is a de- 

 ception produced by comparison with terrestrial objects, or by 

 assigning them, according to the principles of perspective, di- 

 mensions depending upon their places in a supposed less than 

 hemispherical, or rather oblate spheroidical sky, may ascribe 

 all the other concurrent appearances and changes, change of 

 colour, change of place, change, of figure, undulatory changes 

 of limb and outline, to delusions, not only ocular but mental, 

 of the mind as well as of the mind's eye. G. W. J. 



Art. III. On the Native Count ry of the Potato y and on 

 some American Plants . Communicated 63/ A . B . L a m b E rt, 

 Esq., F.R.S., Sec. S^c. 



It has long been a desideratum among botanists to ascertain 

 the native country of the potato, Solanum tuberosum. I beg 

 leave now to offer some communications on that subject, which I 

 have lately received in a letter from the celebrated author of the 

 Flora Peruviana, Don Jose Pavon, who resided many years in 

 South America, dated, Madrid, September 23, 1817, who says, 

 ** The Solanum tuberosum grows wild in the environs of Lima, 

 in Peru, and fourteen leagues from Lima on the coast ; and I 

 myself have found it wild in the kingdom of Chili. I can 

 assure you this is the truth. The Indians cultivate it in great 



