$556 4.4 45 41 8714 8661 8608 8504 8453 8403 8353 8304 8255 41 42 8713 8660 8607 8555 8503 8452 8402 8352 8303 8254 42 43 8712 8659 8606 8554 8502 8451 8401 8351 8302 8253 43 8711 8658 8605 8553 8501 8450 8400 8350 8301 8252 44 8710 8657 8604 8552 8501 8450 8399 8350 8300 8252 45 51 52 55 8705 8652 8599 8547 8495 8445 8394 8345 8295 8247 8704 8651 8598 8546 8494 8444 8393 8344 8294 8246 53 8703 8650 8597 8545 8494 8443 8392 8343 8294 8245 54 8702 8649 8596 8544 8493 8442 8392 8342 8293 8244 54 8702 8648 8596 8543 8492 8441 8391 8341 8292 8244 52 53 THE USE OF THE TABLES. TABLE I. For converting Degrees, Minutes and Seconds into Time. RULE. Take the degrees, minutes and seconds from the first, third, and fifth columns, and against them you have the corresponding times, the sum of which is the time required. Or thus. Multiply by 4; then the seconds produce thirds; the minutes produce seconds, and the degrees produce minutes. 74°. 39'. 57" 4 4. 58'. 39". 48" TABLE II. For concerting Time into Degrees, Minutes and Seconds. RULE. Take the time from the first, third and fifth columns, and against them you have the degrees, minutes and seconds corresponding, the sum of which is the quantity required. EXAMPLE. Reduce 17h. 34'. 19" into degrees, minutes and seconds. Or thus. Bring the hours into minutes, and divide by 4; then the minutes give degrees, the seconds give minutes, and the remainder give se conds. 4)1054'. 19". O′′ 263°. 34. 45" TABLE III. For converting Minutes and Seconds into the Decimal of an Hour. RULE. Take the time from the first and third columns, and against them you have the corresponding decimals, the sum of which is the decimal required. For finding the Length of circular Arcs to Radius Unity. RULE. Take the degrees, minutes and seconds from the first, third and fifth columns, and against them you have the corresponding lengths, the sum of which is the length required. EXAMPLE. What is the length of an arc of 37°. 42′. 58′′? If the radius be not unity, the length may be found by proportion, by saying, unity radius:: length here found the length required. : TABLE V. For finding the Sun's Parallax in Altitude, the apparent Altitude being given. RULE. Find the altitude under the column Sun's Alt. and against it you have the parallax. If the apparent altitude be not found in the Table, the parallax must be found by proportion. EXAMPLE. What is the parallax at the apparent altitude 47°. 27'. 20′′? Hence, 107°. 27′. 20′′:: 1",08 : 0",8, which subtracted from 6",7 leaves 5",9 the parallax. Hence, the altitude, corrected for parallax, is 47°. 27′. 25′′,9. TABLE VI. Contains the mean Right Ascensions and North polar Distances of 36 principal fixed Stars, for the Beginning of 1802; together with their annual Precessions, and proper Motions; all as settled by Dr. MASKELYNE; thence to deduce their places for any other Year. RULE. Multiply the annual precession by the number of years between the given year and 1802, and you get the annual precession for that interval. Then if the given year be after 1802, add the annual precession in right ascension for that interval to the right ascension for 1802, and you get the mean right ascension for the beginning of the given year; and apply the annual precession in north polar distance for the interval, according to the sign, to the north polar distance for 1802, and you get the north polar distance at the beginning of the given year. But if the given year be before 1802, subtract the annual precession in right ascension, and apply the annual precession of north polar distance with a contrary sign. EXAMPLE. What is the mean right ascension and north polar distance of Sirius, at the beginning of the year 1813? Mean right ascension for 1802 Mean right ascension for 1813. 6". 36'. 25",45 6. 36. 54, 93 |
