minutes past three," he proceeds, "when I was again at liberty to continue my labors, the clouds, as if by divine interposition, were entirely dispersed, and I was once more invited to the grateful task of repeating my observations. I then beheld a most agreeable spectacle, the object of my sanguine wishes, a spot of unusual magnitude and of a perfectly circular shape, which had already fully entered upon the sun's disk on the left, so that the edges of the sun and Venus perfectly coincided, forming an angle of contact." I pass over his observations, to quote his account of the feelings with which Crabtree witnessed the spectacle of "Venus on the sun's face." "I had written," he says, "to my most esteemed friend William Crabtree, a person who has few superiors in mathematical learning, inviting him to be present at this Uranian banquet, if the weather permitted; and my letter, which arrived in good time, found him ready to oblige me. . . . But the sky was very unfavorable, being obscured during the greater part of the day with thick clouds; and, as he was unable to obtain a view of the sun, he despaired of making an observation, and resolved to take no further trouble in the matter. But a little before sunset—namely, about thirty-five minutes past three—the sun bursting forth from behind the clouds, he at once began to observe, and was gratified by beholding the pleasing spectacle of Venus upon the sun's disk. Rapt in contemplation, he stood for some time motionless, scarcely trusting his own senses, through excess of joy; for we astronomers have, as it were, a womanish disposition, and are overjoyed with trifles, and such small matters as scarcely make an impression upon others; a susceptibility which those who will may deride with impunity, even in my own presence; and, if it gratify them, I too will join in the merriment. One thing I request: let no severe Cato be seriously offended with our follies; for, to speak poetically, what young man on earth would not, like ourselves, fondly admire Venus in conjunction with the sun, pulchritudinem divitiis conjunctam?"
Many years passed before another transit of Venus took place. This was the transit of 1761, and it affords striking evidence of the interest with which, even at this early epoch, astronomers regarded the transits of Venus, that Dr. Halley, the first Astronomer Royal, prepared a dissertation on the subject of the transit of 1761 forty-five years before it took place. Considering all the circumstances, he made a very fair prediction—in fact, the calculated time when Venus was to be at her nearest to the middle of the sun's face was only about half an hour in error, whereas the epochs first announced by our present Astronomer Royal for the entrance and exit of Venus during the transit of 1874 were one hour and three-quarters of an hour, respectively, in error. I do not propose here, however, to touch on any of the mathematical matters dealt with by Halley, and I shall content myself with quoting the remarks which he made on the importance of observing Venus with due care for the sake of determining the sun's distance:
