A favourable wind arises and dissipates the vapours in the very direction where some important phenomenon will manifest itself, and is to last only a few seconds. The astronomer, exposed to all the transitions of weather, (it is one of the conditions of accuracy,) the body painfully bent, directs the telescope of a great graduated circle in haste upon the star that he impatiently awaits. His lines for measuring are a spider's threads. If in looking he makes a mistake of half the thickness of one of these threads, the observation is good for nothing; judge what his uneasiness must be; at the critical moment, a puff of wind occasioning a vibration in the artificial light adapted to his telescope, the threads become almost invisible; the star itself, whose rays reach the eye through atmospheric strata of various density, temperature, and refrangibility, will appear to oscillate so much as to render the true position of it almost unassignable; at the very moment when extremely good definition of the object becomes indispensable to insure correctness of measures, all becomes confused, either because the eye-piece gets steamed with vapour, or that the vicinity of the very cold metal occasions an abundant secretion of tears in the eye applied to the telescope; the poor observer is then exposed to the alternative of abandoning to some other more fortunate person than himself, the ascertaining a phenomenon that will not recur during his lifetime, or introducing into the science results of problematical correctness. Finally, to complete the observation, he must read off the microscopical divisions of the graduated circle, and for what opticians call _indolent vision_ (the only sort that the ancients ever required) must substitute _strained vision_, which in a few years brings on blindness.[6] When he has scarcely escaped from this physical and moral torture, and the astronomer wishes to know what degree of utility is deducible from his labours, he is obliged to plunge into numerical calculations of repelling length and intricacy. Some observations that have been made in less than a minute, require a whole day's work in order to be compared with the tables. Such was the view that Lacaille, without any softening, exhibited to his young friend; such was the profession into which the adolescent poet plunged with great ardour, and without having been at all prepared for the transition. A useful calculation constituted the first claim of our tyro to the attention of the learned world.