# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

**Re: F tables - "F-Tafel"**

**From:**Hewitt Schlereth

**Date:**2013 Jan 30, 13:23 -0800

Thanks, Dave. Too pricey for me. I'll just figure it's a lot like Dreisenstok and let it go at that. Hewitt Sent from my iPad On Jan 30, 2013, at 1:05 PM, "Dave Walden"wrote: > > F-tafel, tafel zur vereinfachten berechnung von höhenstandlinien. Im auftage des Oberkommandos der Kriegsmarine herausgegeben von der Deutschen seewarte. > Corporate Author: Deutsche Seewarte. > Language(s): German > Published: Hamburg, 1941. > Edition: 3. aufl. > Subjects: Azimuth. > Note: In upper right corner of t.-p.: 2154. > Physical Description: xxiii, 88 p. 30 cm. > Original Format: Book > Original Classification Number: VK 563 .H19 1941 > Locate a Print Version: Find in a library > > ******************* > ABEBOOKS.COM > > F-Tafel. Tafel zur vereinfachten Berechnung von Höhenstandlinien. Im Auftrage des Oberkommandos der Kriegsmarine herausgegeben von der Deutschen Seewarte. > > * Bookseller: Versandantiquariat Lutz Bäsler (Bad Homburg, Hess, Germany) > * Bookseller Rating: 3-star rating > * Quantity Available: 1 > > Add to basket > > Price: £ 42.35 > > ****************************** > 29S[U].—Hamburg, Deutsche Seewarte, publication no. 2154, F-Tafel. > Tafel zur vereinfachten Berechnung von Höhenstandlinien. 3 Auflage. > Hamburg, August, 1941. xxiii, 88 p. 19.6 X 29.2 cm. In the third > edition there were extensions and corrections of the introductory material, > and of 8 of the 11 tables. > The method and principal table of this volume are similar in many respects to those of > H. O. 208 (Dreisonstok, see MTAC, v. 1, p. 79f). The astronomical triangle is divided > into two right spherical triangles by a perpendicular from the zenith upon the hour circle > of the star; U is the co-declination of the foot of the perpendicular, and V is log cos B, > where B is the angle subtended at the zenith by U. By Napier's rules, > tan U = cos I cot L > and > sin B = sin / cos L, > where /, L, and d are the local hour angle, latitude and declination respectively. By applying > another of Napier's rules to the right triangle of which the star is one vertex, the altitude, > h, may be found by > sin h = cos B sin (d + U) > or > log sin h = V + log sin (d + U). > For the determination of azimuth, Z, two more auxiliary quantities are introduced, > P which is the great circle distance from the star to the east- or west-point of the horizon, > and Gr. 4 which is the declination of the intersection of the hour circle of the star with the > prime vertical. Thus, sin t cosd ■>c osP and sin Z = cos P sec h. Also, tan Gr. S = tan L cos t. > 82 RECENT MATHEMATICAL TABLES > In Table F I, with vertical argument, latitude 0(1°)70°, and horizontal argument, > local hour angle 0(4m)6h, three values per page, there are tabulated four quantities, U to > the nearest O'.l, V to 5D, Gr. 5 and P, each to the nearest 0?1. In the second part of > Table F I, the vertical argument is latitude, 70°(1°)90°, and the horizontal argument is > local hour angle 0(4m)6h, nine values per page, three in each horizontal section. > At ths bottom of the vertical columns in Table F I are azimuths; entering the left > hand column with altitude as argument, and moving across the pages horizontally until one > finds under P, the value already copied out, one can drop to the bottom of the column > and read off the azimuth angle. Since the tabulated values of the azimuth angle go up to > 90° only, it is necessary to have another device to determine the quadrant. When the > hour angle is greater than 6b, the azimuth is measured from the elevated pole; when the > local hour angle is less than 6h and L and d are of opposite name, the azimuth is measured > from the depressed pole. If the local hour angle is less than 6h and L and d are of the same > name, the azimuth is measured from the elevated or depressed pole according as the declination > is greater or less than the quantity Gr. a. > In case the altitude is great, or the azimuth near 90°, the value of the azimuth may be > poorly determined by the use of Table F I. In such a case, it will be noted that the value > of P lies below a dotted line running across the page. One must then use instead Table > F XI, which gives P to the nearest minute of arc and the variation in P corresponding to > 1' change in d or h. > Table F II is a table of log sin x, x = [0(0'-1)6°(1')90°; 5D], with generous tables of > proportional parts. > Tables F DI and F IV represent the principal advantages this volume possesses over > other similar tables; they permit one to determine the corrections (to the nearest 0!1) to > the computed altitude corresponding to slight changes in time (up to 2m by 10* steps) or latitude > (up to 30' by 1' steps) respectively. In both cases, one can interpolate very easily by a > shift of the decimal point. Table F III is a well-designed triple-entry table occupying only > five pages; one starts down the column at the left headed by the value nearest the assumed > latitude, stops at the value nearest the computed azimuth and moves to the right to the > column headed by the number of seconds change in time. Table F IV is a small doubleentry > table on a single page; the vertical argument is azimuth 0(5°)20°(2°)90°, and the > horizontal argument is change in latitude, l'(l')10'(10')30'. These two tables allow one to > work either with an assumed position or with a dead reckoning position. > Table F V is for changing time into angular measure and conversely. Table F VI gives > the corrections for refraction, semi-diameter and parallax to be applied to the altitude > (3°-90°) of the lower- or upper-limb of the moon; there is a supplementary table for height > of eye. Table F VU gives the combined correction for refraction and height of eye (0-30 > meters) to be applied to the altitudes (3°-90°) of fixed stars or planets. Table F VIH yields > the correction for refraction, semi-diameter and height of eye (0-30 meters) to be applied > to altitudes (3°-90°) of the sun's lower limb; there are also two auxiliary tables to provide > corrections to the altitudes to take care of the varying semi-diameter of the sun through the > year, and for the case where the sun's upper limb was observed. The latter takes only a > very small amount of space and would seem to be quite worthwhile. Tables F IX and F X > provide similar corrections for use with the bubble sextant. > The tables are well printed on a good grade of paper. In a number of cases, the rules > needed to make decisions as to quadrants, etc. are printed on each page. As for the accuracy > of the tabulated values, only a few rounding off errors of a unit in the last place were > discovered in a brief examination. > Charles H. Smiley > Brown University > ---------------------------------------------------------------- > NavList message boards and member settings: www.fer3.com/NavList > Members may optionally receive posts by email. > To cancel email delivery, send a message to NoMail[at]fer3.com > ---------------------------------------------------------------- > > > > > View and reply to this message: http://fer3.com/arc/m2.aspx?i=122177 > >