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HISTORY OF PHYSICAL ASTRONOMY.

unspeakable delight, tlie round black spot representing the planet depictedupon the white circle. According to Horrocks , he was so captivated bythe spectacle, that he gazed upon it immovably for some time, and whenhe recovered himself, the clouds had again obscured the sun, so that hewas unable to make any accurate measurements. He, however, drew adiagram of the position of the planet, which Horrocks found to agreeexactly with his own observations. He estimated the diameter of theplanet at T J T) ths of the solar diameter, or about V 3", supposing withHorrocks that the latter was equal to 30'.

Thus did two young men, cultivating astronomy together in a state ofalmost complete seclusion in one of the northern counties of England,enjoy the privilege of witnessing a phenomenon which human eyes hadnever before beheld, and which no one was destined again to see untilmore than a hundred years had passed away*. Unfortunately, a prema-ture death deprived their country of the two individuals who exhibitedsuch enthusiasm in the cause of science. Horrocks was a young man ofextraordinary genius, whose name would assuredly have formed a house-hold word to future generations, if his career had not been so soon broughtto a close. It may perhaps not be uninteresting to mention some of thefew facts which are known respecting the two youthful astronomers.

Jeremiah Horrocks was born at Toxteth, near Liverpool , in the year1019, of parents who appear to have been in rather straitened circum-stances. Having received the rudiments of instruction at his nativeplace, he subsequently completed his education at Emmanuel College ,Cambridge. About the year 1033, he seems to have been first led toturn his attention to astronomical pursuits. In one of his posthumousfragments, he has described, with all the fervour of youthful enthusiasm f,the state of his feelings at this time, and the means by which lie suc-ceeded in vanquishing the difficulties of his position; for it must beborne in mind that, in those days, there was no branch either of mathe-matical or physical science taught at Cambridge. “ I felt great delight,”says he, “ in meditating upon the fame of the great masters of science,such as Tycho Brahe and Kepler, and sought at least to emulate themin my aspirations. I imagined that nothing could be nobler than tocontemplate the manifold wisdom of my Creator amid so great a pro-fusion of works; and to behold the pleasing variety of the celestial mo-tions, the eclipses of the sun and moon, and other phenomena of thesame kind, no longer with the unmeaning gaze of vulgar admiration, butwith a desire to know their causes, and to feed upon their beauty by acloser inspection of their mechanism.”]; Serious obstacles, however, opposedthemselves to the realisation of these ideas by Horrocks . His humblecondition in life was by no means favourable to the tranquil prosecutionof astronomical researches. He had no teacher who could give him any

* The transits of Venus happen invariably either in June or December, according asthe planet is passing through the descending or the ascending node of its orbit. Theintervals between the successive transits counted in years are—8, 105); 8, 121);8, 105) ; &c., &c. Two transits of the planet at the ascending node will happen in thenineteenth century, one on Dec. 8, 1874, and another on Dec. 6, 1882. The transit of1039, witnessed by Horrocks and Crabtree, is the only phenomenon of this kind that hasbeen hitherto observed at the ascending node.

t “ On voit que Horrocks etait jeune et enthousiaste, mais cette jeunesse et cetteenthousiasme annoncaient un homme vraiment distingue.” (Delambre, Hist. Ast. Mod.,tom. ii., p. 497.)

J Opera Posthuma, p. 2.