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history of physical astronomy.
tlie failure of Gassendi ’s attempt to obtain a view of the planet during thetransit of 1631, that the existing generation of the human race would longhave passed away before another occasion would present itself of observinga phenomenon of so interesting a nature. In the year 1039, however, theplanet passed again over the sun’s disk. On this occasion the transittook place unknown to any person living, with the exception of two in-dividuals who enjoyed the gratification of witnessing the phenomenon.The fortunate observers were Jeremiah Horrocks and William Crabtree ,two young men residing in the north of England, devoted enthusiasticallyto the study of astronomy. Horrocks has given an account of the transitof the planet, as seen by himself and his friend Crabtree, in an interestinglittle dissertation on the subject entitled “ Venus in Sole visa.” He hadbeen engaged in calculating the places of the planets by means ofLansherg’s tables, which their author had boasted to be unequalled inpoint of accuracy; but, on comparing the results with observation, he wasmortified to find that the discordances were of such magnitude, as torender his labours almost of no value. This circumstance calls forth theindignation of the young astronomer, who contrasts the tumid arrogance ofthe Belgian calculator with the unobtrusive merits of the illustrious Kep-ler . Lausberg, with as little modesty as truth, had vauntingly cited thewords of the Homan poet,—
“ Quantum lenta solent inter viburna cupressi,”
as affording a just idea of the superiority of his tables over all other ex-isting labours of a similar kind. Horrocks remarks, that however inap-propriate the simile of the poet may be when so applied, it may be usedvery justly to represent the surpassing excellence of the ltudolphineTables. Indeed, there could not be wanted a clearer indication of thegenius of Horrocks than is afforded by the intuitive sagacity with whichhe seems to appreciate the value of Kepler ’s discoveries; for it is to beborne in mind that the prejudices in favour of the ancient system of as-tronomy had not yet been wholly eradicated from men’s minds*.
It is a curious fact, however, that the tables of Lansberg, howevererroneous, were instrumental in revealing to Horrocks the interesting factthat Venus would pass over the sun’s disk in the month of December,1639. He had found that Kepler ’s tables displaced the planet in lati-tude about 8' towards the south, while on the other hand the tables ofLansberg indicated a much larger error in the opposite direction. Duringits conjunction with the sun in December, 1639, the planet appeared byKepler ’s tables to pass a little below the sun, while, on the other hand,those of Lansberg brought it upon the upper part of his disk. He sus-pected, therefore, that the planet would actually pass over the solar disktowards its lower extremity, and a more complete investigation of the sub-ject assured him of the accuracy of his surmise. By an exact calculationof the time of conjunction, he found, in fact, that the planet would enterupon the solar disk on the 24th of November, O.S., 1639, a little beforesunset. Owing to the shortness of the interval that was to elapse pre-vious to the actual occurrence of the transit, he was unable to announcewith sufficient publicity the interesting result at which he arrived, so as