Fourth. When they are on different sides.
For instantaneousness of observation, the equatorial has great advantage over the circle or sextant; for being truly placed in the meridian beforehand, the telescope may be directed sufficiently in advance of the moon's motion, for time to note its place on the equatorial circle, before she attains that point. Then observe, until her limb touches the cross-hairs; and in that instant direct the telescope to the star; that completes the observation, and the place of the star may be read at leisure. The apparatus for correcting the effects of refraction and parallax, which is fixed on the eye-tube of the telescope, saves time by rendering the notation of altitudes unnecessary, and dispenses with the use of either a time-keeper or portable pendulum.
I have observed that, if placed in a desert where neither meridian nor latitude is yet ascertained, the equatorial enables the observer to find both in a few hours. For the latitude, adjust by the cross-levels the azimuth plane of the instrument to the horizon of the place. Bring down the equatorial plane to an exact parallelism with it, its pole then becoming vertical. By the nut and pinion commanding it, and by that of the semi-circle of declination, direct the telescope to the sun. Follow its path with the telescope by the combined use of these two pinions, and when it has attained its greatest altitude, calculate the latitude as when taken by a sextant.
For finding the meridian, set the azimuth circle to the horizon, elevate the equatorial circle to the complement of the latitude, and fix it by the clamp and tightening screw of the two brass segments of arches below. By the declination semicircle set the telescope to the sun's declination of the moment. Turn the instrument towards the meridian by guess, and by the combined movement of the equatorial and azimuth circles direct the telescope to the sun, then by the pinion of the equatorial alone, follow the path of the sun with the telescope. If it swerves from that path, turn the azimuth circle until it shall follow the sun accurately. A distant stake or tree should mark the meridian, to guard against its loss by any accidental jostle of the instrument. The 12 o'clock line will then be in the true meridian, and the axis of the equatorial circle will be parallel with that of the earth. The instrument is then in its true position for the observations of the night. To the competence and the advantages of this method, I will only add that these instruments are high-priced. Mine cost thirty-five guineas in Ramsden's shop, a little before the Revolution. I will lengthen my letter, already too long, only by assurances of my great esteem and respect.
TO —— NICHOLAS.
Monticello, December 11, 1821.
Dear Sir,—Your letter of December the 19th places me under a dilemma, which I cannot solve but by an exposition of the naked truth. I would have wished this rather to have remained as hitherto, without inquiry; but your inquiries have a right to be answered. I will do it as exactly as the great lapse of time and a waning memory will enable me. I may misremember indifferent circumstances, but can be right in substance.
At the time when the republicans of our country were so much alarmed at the proceedings of the federal ascendency in Congress, in the executive and the judiciary departments, it became a matter of serious consideration how head could be made against their enterprises on the constitution. The leading republicans in Congress found themselves of no use there, brow-beaten, as they were, by a bold and overwhelming majority. They concluded to retire from that field, take a stand in the State legislatures, and endeavor there to arrest their progress. The alien and sedition laws furnished the particular occasion. The sympathy between Virginia and Kentucky was more cordial, and more intimately confidential, than between any other two States of republican policy. Mr. Madison came into the Virginia legislature. I was then in the Vice-Presidency, and could not leave my station. But your father, Colonel W. C. Nicholas, and myself happening to be together, the engaging the co-operation of Kentucky in an energetic protestation against the constitutionality of those laws, became a subject of consultation. Those gentlemen pressed me strongly to sketch resolutions for that purpose, your father undertaking to introduce them to that legislature, with a solemn assurance, which I strictly required, that it should not be known from what quarter they came. I drew and delivered them to him, and in keeping their origin secret, he fulfilled his pledge of honor. Some years after this, Colonel Nicholas asked me if I would have any objection to its being known that I had drawn them. I pointedly enjoined that it should not. Whether he had unguardedly intimated it before to any one, I know not; but I afterwards observed in the papers repeated imputations of them to me; on which, as has been my practice on all occasions of imputation, I have observed entire silence. The question, indeed, has never before been put to me, nor should I answer it to any other than yourself; seeing no good end to be proposed by it, and the desire of tranquillity inducing with me a wish to be withdrawn from public notice. Your father's zeal and talents were too well known, to derive any additional distinction from the penning these resolutions. That circumstance, surely, was of far less merit than the proposing and carrying them through the legislature of his State. The only fact in this statement, on which my memory is not distinct, is the time and occasion of the consultation with your father and Colonel Nicholas. It took place here I know; but whether any other person was present, or communicated with, is my doubt. I think Mr. Madison was either with us, or consulted, but my memory is uncertain as to minute details.
I fear, dear Sir, we are now in such another crisis, with this difference only, that the judiciary branch is alone and single handed in the present assaults on the constitution. But its assaults are more sure and deadly, as from an agent seemingly passive and unassuming. May you and your cotemporaries meet them with the same determination and effect, as your father and his did the alien and sedition laws, and preserve inviolate a constitution, which, cherished in all its chastity and purity, will prove in the end a blessing to all the nations of the earth. With these prayers, accept those for your own happiness and prosperity.