idea for that occasion. But, if a sound one, it should not be abandoned. Those deserts are yet to be explored, and their geography given to the world and ourselves with a correctness worthy of the science of the age. The acquisition of the country before Captain Lewis' departure facilitated our enterprise, but his time-keeper failed early in his journey. His dependence, then, was on the compass and log-line, with the correction of latitudes only; and the true longitudes of the different points of the Missouri, of the Stony Mountains, the Columbia and Pacific, at its mouth, remain yet to be obtained by future enterprise. The circumstance which occasions a recurrence of the subject to my mind at this time particularly is this: our legislature, some time ago, came to a determination that an accurate map should be made of our State. The late John Wood was employed on it. Its first elements are prepared by maps of the several counties. But these have been made by chain and compass only, which suppose the surface of the earth to be a plane. To fit them together, they must be accommodated to its real spherical surface; and this can be done only by observations of latitude and longitude, taken at different points of the area to which they are to be reduced. It is true that in the lower and more populous parts of the State, the method of lunar distances by the circle or sextant, and time-keeper, may be used; because those parts furnish means of repairing or replacing a deranged time-keeper. But the deserts beyond the Alleghany are as destitute of resource in that case, as those of the Missouri. The question then recurs whether the equatorial, without the auxiliary of a time-keeper, is not competent to the ascertainment of longitudes at land, where a fixed meridian can always be obtained? and whether indeed it may not everywhere at land, be a readier and preferable instrument for that purpose? To these questions I ask your attentions; and to show the grounds on which I entertain the opinion myself, I will briefly explain the principles of the process, and the peculiarities of the instrument which give it the competence I ascribe to it. And should you concur in the opinion, I will further ask you to notice any particular circumstances claiming attention in the process, and the corrections which the observations may necessarily require. As to myself, I am an astronomer of theory only, little versed in practical observations, and the minute attentions and corrections they require. I proceed now to the explanation. A method of finding the longitude of a place _at land, without a time-keeper_.