I UC-NRLF O B 3 066 711 ■ HOW TO FIND THE TIME AT SEA IN LESS THAN A MINUTE; BEING NEW AND ACCURATE METHODS, • WITH SPECIALLY ADAPTED TABLES. A. G. JOHNSON, R.N. AUTHOR OF On finding the Latitude and Longitude in Cloudy Weather/' Ac. SIXTH EDITION.. Xonfcon : PUBLISHED BY J. D. POTTER, Admiralty Agent far Charts, 145, MINORIES, E. 1. 1918. [all rights reserved.] THREE SHILLINGS. HOW TO FIND THE TIME AT SEA IN LESS THAN A MINUTE ; BEING NEW AND ACCURATE METHODS, WITII SPECIALLY ADAPTED TABLES. A, C. JOHNSON, R.N. AUTHOR OP On finding tte> Latitude and Longitude in Cloudy Weather," <&c. SIXTH EDITION Xon&on : PUBLISHED BY J. D. POTTER, Admiralty Agent for Charts, 145, MINOHIES, E. 1. 1 did. [all rights reserved] THREE SHILLINGS. PREFACE TO THE EIFTH EDITION, The Tables (A) (B) (G) as given in this edition, are intended for general use and although contracted so that all the logs requisite for working a "Chronometer" are displayed at one view, the time may be found by them within a second or two of that obtained by the ordinary rules. The special Table (D) may be used when the sky is clear, and the observation can h& taken in the manner indicated ; the advantage of this being that only a single logarithm has to be looked out after the observation has been taken, so that finding the time is reduced to the most simple and expeditious process in the whole range of nautical astronomy (vide p. 8), whil9 in point of accuracy it is not inferior to the former method. The very favourable notice accorded to these little tables by Lieut. English, B.N. , in bis highly scientific and valuable articles on Navigation which have from time to time appeared in the "Field" newspaper, and the marked approval which they have met with from numerous offioers of our own and foreign services, as well as from the mercantile marine, have encouraged the author to introduce into this edition sundry alterations .and improvements which he hopes will still further add to the usefulness of the book. Dartmouth, !$07. 385614 CONTENTS, -^E- Pags D ., ith the latitude at Moon... 7 D by Chart 8 teeomdM ... ... 8 -.ions 9 To n^d the Time simultaneously a ... 10 ling the Time byTal E | 11 a Star .. 19 - J. . 12 longitude for error in latitude 12 e 13 . (es 15 >bserred altitude 10 16 20 2G 38 nth, ... 28 INTRODUCTION. The practice of working out the sights for longitude with the DM. latitude, and of subsequently correcting the resulting longitude for the error in this latitude, is, in the present day, generally followed. Now it will make no difference in the ultimate result if, instead of the D,R. latitude an twinned latitude approximating to it be used— the object being to reduce the meridian zenith distance (ichkh is the suv> or difference of the latitiule and decimation, according as they are of opposite or like names) to an exact number of degrees, so that it may correspond with the M.Z.D. in Table (D). For a like reason the altitudo is taken to an exact degree, a matter of perfect simplicity to a practised observer, and, when taken, no further correction is necessary. Should, however, the weather be cloudy, and the altitude be taken in the usual way, we can easily correct the log. from Tablo (D) for the minutes of altitude, as shown on p. 12. The observation is supposed to be taken r.nder the usual conditions as to the bearing hum the meridan, and to an exact degree by allowing the correction in altitude the opposite way. Thus for 20 ft. and 80°, the correction in altitude for the sun is + 10' ; and if the index error be -f- 1', the combined correction is + 11'. If, therefore, the sextant be set at 29° 49', the true altitude of the Sun's .centre- will be 80° at the moment the lower limb is in contact with the horizon. For a star the correction in altitude must bo added instead of sub- tracted, but the index error must be applied as before. Thus, for 20 ft. and 30°, the correction in altitude -is -6', and if the index error be -f 1' the combined correction will be — 5' ; if, therefore, the index be set at 80° 5', the true altitude will be 80° when the star is in contact with the horizon. Tho longitude deduced from the time thus found is to be corrected for the srror in the assumed latitude in the usual way. {Vide p. 12.) TO FIND THE TIME. BY TABLE (D). I. — Assume a latitude that will make the M.Z.'D. an exact number of degrees.* and let this be called Lat. A. II. — For this M.Z.D., and the altitude take out the logarithm from Table (D). This added to the log. secants of the assumed latitude and declination, -will be tfee log. versine of the hour angle, which will be found in the part of Table (B) indicated by the approximate time, or hour angle. If the body be East of Meridian, subtract the H. A. found as above from 24 hours. The longitude deduced from this time 13 to be corrected for the error in the assumed latitude by Table (E). EXAMPLES. I.-LafcD.B. 30°25'N. Dec. 19° 45' S. Alt. 28°. Itfit. A. 30° 16' N. log sec. G3(» «>ec. 20 45 S, ,, ,. 2fi3 Alt, 28 l l °3^ b -^ ™ m H.A. 2h, 32m. 37s. log vors. 328? II.— Lat.D.R. 52°20'N. Dec. a 80' J*. Alt. 10°. Lat. A. 52° 30' N. log. sec. 2JS6 D*c. 1 30 N. „ „ d BKZ.D. 61 0) Aft. 19 fl«>g. iob. tD, 4826 H.A. 3h. 59m. 44s.... lo^' vers. oD8'2 The assumed latitude need not differ from the I). JR. latitude 'by more than 30', and will not, therefore, ati'ect the accuracy of the result. Ou the next page is shown the practical application of the above in finding the longitude at noon, and the longitude corresponding to Hit- D.K. latitude. * To do this make tbe minutes of latitude equal to the minutes of declination, when they are of the name name, :md when they are of contrary names subtract the minute* in the declination ft om 60' to obtain the minutes of. assumed latitude. HI.— At 8.30 a.m., in lat. D.R. 40° 35' N., G.A.T. by chronotnete* 22h. 20m. 20s., true alt. 30°, run to noon N.N.W. 30', lat. by raer. alt at noon 40° 52' N. Required the true longitude at noon. I Mi. A. 40" 30' N. 1190 Az. by Tables.* Dec. 3 SON. 8 ;S. 66° E. M.Z.D. 37 0) Lat. 40° N. Alt. 30 0|' H.A. 8.30 1 H.A. 3h.-S0m.40i. 5949 S.A.T. 20 29 20 G.A.T. 22 20 20 1 51 = 27* 15 p W., at 8.30 a.m. (long. A) How to find the longitude simultaneously with the latitude at NOON. Lat. A. 40° 30' N. Long. A. 27° 45' W. Run 28 N. Run 13 W. Approx. lat. 40 58 N T . Appro*, long. 28 W. Lat. mcr. ) 4Q - 2 N Cor. -53 x 3 g W. Alt./ Cow. S. True long. 23 34 W. If it were required to find the longitude corresponding to the D.R. latitude at 6.30 a.m., we should have :— Lat. A. 40^ 30* K. Lour. A. 27° 45' W. h.li. 40 35 K. Cor. 58 x 5 , 3 E. Corr. 5 N. Approx. long. I 27 42 w at 8.30 f "' * H w ' The correction for longitude, *56', is taken from Table (E). To name the correction for the longitude, vide page 12. The bearing found by Azimuth Table, when exceeding 90 3 , must be subtracted from ISO'', and reckoned from the opposite point — thus, N. 120 W. would be S. CO W., &c. Those given In •* Cloudy Weather " may be used ior this purpose. To find the position AT NOON by the Chart. Through the point given by the approximate latitude and longitude at noon, draw the position line, or (in this case) the line at right angles to S. 60° E. Then where this is cut by the parallel of the true latitude will be the true place of the ship. To explain how in actual practice the Time may be found IN A FEW SECONDS. As the declination^ and therefore the assumed latitude which depends on it, are known before the observation is taken, we are already provided with the M.Z.D., and the two log secants ; a single logarithm only will then be required to complete the process. Thus, in Ex. I., p. 6, the declination being 19° 45' S., and. the ship bctwees 80° N. aad 81° K., it is evident that the assumed latitude must be $0° 15 s N., therefore ns have — Lat, A. 30° 15' N. 636 Dec. 19 45 S. 268 M.Z.D. 50 899 N. Having subsequently observed the altitude to be 28° we have — N. 8tf9 Log. tab. (D) 2888 h. HJ, 3, Log. vers. 8287 - 2 82 27 The time is thus found in a fern seconds and with summers t accuracy for all practical purposes at sea. Application of the above Principle to Sliding the Position by TWO OBSERVATIONS. Let us suppose that the foregoing observation has been taken ; that the longitude deduced from it i& 20° 45' W«, and that the ship has run E.S.E. 22' till 4.80 *.m., we have — Lat. A. 80° 15' N. Long. A. 20* 45' W. Run 8 S. Bun 28 E. Lat. B. 80 7 N. Long. K 20 22 W. The declination being now 19° 47' S<, suppose, and the ship being between iat. 80° and 31° K., we assume 80° 13' N, for lat, C. Hence we have Lat. C. 80^ 18' N. 685 Dec. 19 47 B. 264 M.Z.D. 50 899 (N.) The second altitude is now taken, and is found to be 8°, therefore, as before : — N. 899 Log. tab. (D) 7021 h. in. s. 7920 = 4 80 82 Now, supposing that the longitude resulting from this time is 20° 52' W. (or long. C), we have then :— Lats. Longs. Az. Position Lines. B 30° 7' N. B 20° 22 W. S. 41° W. N. 49° W. G 80 18 N. C 20 52 W. S. 61 W. N. 29 W. Laying down B and C on the chart, and drawing the corresponding position lines, the point in which they intersect will be the true place of the ship at the time of the second observation. The above principle is equally applicable to two stars, taken in the morning or evening twilight, either simultaneously or in quick succession ; and, .as it involves only about a quarter of the work of an ordinary 1 Sunnier,' and will give just as good results, it is strongly commended to the notice of the practiqal navigator. Obs. —The difference of bearing should not be less than 1£ or 2 points ; and, as a general rule, should exceed the less bearing. This applies to all heavenly bodies. to To find the Time SIMULTANEOUSLY with the Altitude. As shown on page 8, we can determine beforehand the M.Z.D. and N. ; we can therefore take out the H.A. for a few consecutive degrees, which will include the altitude at the time we wish to take the observation. Thus, for M.Z.D. 50°, N. 899, and altitudes 29°, 30?, 81°, we have : 899 899 899 1986 1547 1064 2446 1963 (a) 2h. 25m. 18s. (b) 2h. 17m. 53s. (c) 2h. 10m. 14s. If, therefore, the true altitude is found to be either of the above s, the corresponding H.A. is known without further calculation. The altitudes to be selected will, of course, depend on the time at which it is intended to take the observation. Suppose, for instance, we fix upon 8 a.m., and that the M.Z.D. is 50°, and N. 899, as before. Subtracting N. from the log vers. H.A., we look for the remaining log under the M.Z.D. 50°, hi Table (D), when in a line with it we find the altitude thus : — . Log. vers. 4h. = 6990 Tab. (C). N. = 899 Log. alt, = 6091 Now, in the column M.Z.D. 50°, we find that 6091 comes between the logs, of 13 J and 14°. Hence we may select 18°, 14°, and 15°, fo* which we take out the time, as above. So that, if required, while one person is taking the altitude, a second may be finding the time from the Tables. If, owing to clouds, the altitude cannot be observed as explained, the log. from Table (1)) may easily be corrected for the minutes of altitude, us shown on p. 12. From the above hour-a)igles and altitudes may he found the Bearings, by tht Azimuth Tobies, and thence the Variation, tic., */' required. 11 ON FINDING THE TIME BY TABLES (A), (B), (C). (These Tables are to be used when the observation is taken in the usual way, and as they are all on the same opening, a great saving of time and trouble is thereby effected.) From Table (A) are taken the nat. versines of the Z.D. and M.Z.D., and the H.A. corresponding to their difference. The log. versine of this H.A., Table (C), added to the log, secants of latitude and declination, Table (B), will be the log. versine of the H.A., to be taken from the part of Table (C), indicated by the approximate time.. EXAMPLES. I.--rAt about 4h. 40m. p.m., in lat. 10° 35' N.,' ©Z.D. was 76° 32', and declination 23' 23' ~S. Lat. 10° 35 r N. 74 sec. Tab. A. Dec. 23 2& S. 372 ,, M.Z. 33 58 ZJ>. 76 32 4h. 24m. 49s. 4 40 46 7756 log vers. 8202 N. Vers. 1706 7672 Diff. 5966f H.A. IL—At about 4h. 10m. p.m., in lat. 10° 5' N., ©Z.D. was 63° 35', and declination 23° 19' N. Lat. 10° 5* N. 67* sec. Tab. A. Dec. 23 19 N. 370* „ N. Vets. 266* M.Z. 13 14 ^ „ 5551 Z.D. 63 35 Diff. 5285 4h. 7m. 28s. 7230 log. vers. H.A. 4 21 48 7667 „ When the sun is west of mer. the H.A. is apparent time. When east, subtract the H.A. from 24 hours. When the sum of the logs, exceeds four figures, reject the fifth figure on the left. The parts marked with an asterisk may be written down before the observation is taken, thus enabling the remaining part of the calculation to be quickly gone through. In usiog Table (C) it may sometimes be required to subtract an apparently greater logarithm from one apparently less, in which case the latter must be increased by 10,000, which is done by prefixing 1. Thus : 0026-9970 = 10028-9970=0056. t Here diff. 5966 gives 4h. 24m. 49a. by Table (A). And 4h. 24m. 49s. give log. vers. 7756 by Table (C). In Ex. II. 5285 gives 4h. 7m. 28s. by Table (A), and 4h. 7m. 28s. give log. vers. 7230 by Table (C). 12 TO FIND THE TIME BY A STAR. Find the hour-angle as in either of the preceding examples ; then to the star's H.A. add its R.A., and from the sum (increased, if necessary, by 24h.) subtract the R.A. of the mean Sun. The remainder will be mean time at ship. The longitude is then found in the usual way. N.B. — If the star is East of meridian, subtract the H.A. found as above from 24 hours. The star's bearing, when required, may be taken from Burdwood's Tables, or from ''The Bearings of the Principal Bright Stars," by the Authoi, published by J. D. Potter, London, price 3a. To take out the Log. from Table (3D) when there are minutes in the Altitude. Take the difference of the logs, for the two degrees of altitude between which the given altitude lies, multiply it by the minutes expressed as the decimal of a degree*, and subtract. Thus for M.Z.D. 10° and Alt. 20° 24' We have for Alt. 20° 6081 Diff. 112 x -4;-- 45 Log. required 8036 Again, for M.Z.D. 4°, and Alt. 25° 20' We have 7S96 Diff. 120 x '88- 40 Log. required 7C56 As the logs, decrease, they are conveniently arranged for subtracting. To correct the longitude for an error in the latitude. Table (E) gives the correction for 1' error in the latitude — this, multiplied by the latitude correction, will be the correction required. To name the Correction. Under the sun's bearing, at the time of observation, write the opposite bearing, and connect the letters diagonally, Thus for Bearing N.W. X We Jiavo S.E. * The multiplier nifty be taken from Table (D), p 25. 18 Which shows that a North correction of latitude gives an East correction of longitude, and vice versa. Ex. lat 80° N. Bearing N. 80° E., corr. of lat. 20' S. Lat. 80° i ntnn N '?' Az.800^ '- 20 s / • . • The correction = '-20 x 20 or 4' E. The name of the correction may also be found by reversing the first letter of the bearing, thus for N.E. we Lave S.E., showing that a corr. S. gives E. and rice verm. EXAMPLES FOR PRACTICE. Finding the Hour- Angle by Table D . (1.) Lat. assumed, 50' 30' X. Dec. V SO' X. Alt. 2C II.A. afibut 3^ his. l±J „ 10 45 S. „ 10 15 X. ,, 15 4 „ (2) ,. 7 13 X. „ 2 15 X. ,. ">o 2J ., (4.) ., 30 40 X. „ \ 20 S. 11 ,.■ H .. (5.) ,, 29 10 X. ., t2 10 X ANSWEBS. „ 33 4 ., (1.) 3h. 30m. lGs. (2.) 3h. 59m. 12a. <3.) 2h. 31m. 3s (4.) 2h. 19m. Is, (5.) 3h. 55m. 37a. Finding the Hour- Angle by Tables (A), (B), (C). (1). True Lat. 50'' 21' N. Dec. 12 3 10' N. Alt. 40° 30' H.A. about 2J hrs. (2). ., 40 30 S. „ 10 51 X. „ 35 17 „ „ 1J .. (3). „ 20 10 X. ., 10 20 X. ■ „ 50 15 „ „ 2| „ (4). ., 2 5 8. „ 1 3 S. „ 60 10 2 „ ANSWEBS. (1.) 2h. 34m. 33s. (2.) lh. 21 m. 303. (3.) 2h. 40m. 13s. (4.) lh. 59m. J7s. 14 The M Z.D. and N., having been previously determined ; to find the Hour-Angle. (1.) M.Z.D. 50' X. 295 Alt. 20 9 H.A. about. 3 hoars. (2.) ,. 48 X. 1216 „ 17 „ „ 4£ „ (». „ 45 X. 312<$ „ 15 „ ,, 6§ „ . AXSWERS. (1.) 8h. 9m: 12s. (2.) 4h. 20m. 54s. (3.) 5h. 41m. 52s. Correcting Log. Table D, for Minutes. (1.) M.Z.D. 10' Alt. 40* 20' 42.) „ 20 „ 13 20 (8.J „ 30 „ 20 4h AXHWBRS. (1.) 32*4. (2.) 5889. (».) "iW.i. Correcting the Longitude, for an Error in Latitude. 11.) La*. 50" X. Bearing S. 00' E. Coir, for hat. 2W X. (2.) „ 40 S. „ S. 70 W. „ 10 »S. (3.) „ 20 X. „ X. 75 h. „ 15 N. AXSWEHS-CORUECTIOXS. (J.) 18' E. (2.) 5'E. (3.) 4'W. EXPLANATION OF THE TABLES. Wlten a logarithm has to be taken out in two parts, place the forefinger of i^e left-hand on one part and the pen on the other, when the tipo parts ore easily added together at night* • Tho parts for the minutes seldom exceed two figure*, and frequently only a single figure fc reruired to be added. 15 Tab. (A). To take out Nat. Vers. 31° 53' : We have 30° at the Bide, and 1° 45' at the top, or 31° 45' = 1496, and the parts for 8' (to make up 58') are 12 — which, being added, we have 1508 ; the Nat. Vers, required. To take out Nat. Vers. 59° 25|' : We have 55° at the side, and 4° 15' at the top, or 59° 15' = 4887, and the parts 10J' (to make tip 25V) are 26 — which, being added, we have 4913. This Table is arranged in two parts. The second being supposed to be a continuation of the first from left to right,* so that any veraine not appearing in the first part will be found in the second, and vice versa. To take out the time. for Nat. Vers. 4188 : The Nat. Vers, next less is 4157, which gives 3h. 37m., and the cliff. , 31, gives 54 seconds: hence the time is 8h. 37m. 54s. Conversely : The Nat. Vers, of 3h. 37m. 54s. is 4188, for 3h. 37m. gives 4157, and 54s. give 31— which, being added, we have 4118 as above, fables (B) and (C) are used in the same manner. The use of Table (D) when there are minutes in the altitude is explained on p. 12. To convert Arc into Time by Table (A.). Ex. Convert 76° 40' into time: We have 76° 30' = 5h. 6m., and K>* = 40s. ■.• 76°40' = 5h. 6m. 40s. Conversely: 5h. 6m. 40° = 76° 40', for 5h. 6m. = 76° 30*, and 40s. =10' ♦.- 5h. 6m. 40s. = 76° 4tf. For an Arc greater than 90° subtract 90° ; convert the remaining degrees into time and add 6h., and for time exceeding 6h., subtract 6 hrs., convert the remaining time into Arc and add 90°. To find the Natural Versine of an Arc greater than 90° . Subtract the Nat. Vers, of its supplement from 19999. Thus for 120° 80' (whose supplement is 58° 80') we have Nat. Vers. 59° 80' = 4925. • . • 19999 -4925 = 15074 = Nat. Vers. 120° 80* Conversely: Nat. Vers. 15074 = 120° 80'. For 19999 -15074 ^492$ = 59° 30'. And 180°- 59° 80' =120° 30'. * In the. same way as Table B, To convert a Nat. Vers, into a Lor/. Vers. : E . — Convert Xat. Vera. 7IG8 into a Log. Versirus. By Table (Aj, Nat. Vers. 7168= 4h. 54m. 12s.=Log. Vers. 8564, Table (C).* III. To find the Hour- Angle of a Star, referred to the Meridian below the Pole. To obtain the M.Z.D. in this case add together latitude and declina- tion and subtract the sum from 180°, then proceed as before. EXAMPLE. Lat. 50° 20' N. Dec. 48° 80' N. Z D. 79° 40' • M.Z.D. 81° 10' 8465 Lat. 50° 20 f 1950 *Z.D. 79 40 8207 Dec. 48 80 1787 Nat. Vers. 258 = Log. Vers. 4114 H.A. Ih. 20m. 28s. 7851 If the M.Z.D. exceeds 90°, find its Nat. Vers, as above. As in this particular case the M.Z.D. will always be greater than the Z.D., it is written down first. TABLES FOR CORRECTING THE OBSERVED ALTITUDE. ( .) CORR FOR SUN'S OBS. ALT. + CORK. FOR STAR'S OBS . ALT. - HEIGHT IN FEET. HEIGHT IN FEET. ALT. 5 S 10 15 20 25 30 35 40 45 50 55 60 *tr. 5 iC 15 20 25 SO 35 40 45 50 58 60 6 s 4 4 3 3 2 2 , , I o 6 IO n 12 «3 '3 14 '4 '5 '5 15 IS rti 7 7 6 S 4 4 3 3 3 2 2 1 i ■i 9 IO II !2 12 '3 ■3 »4 14 14 IS '5 8 7 6 6 5 5 4 4 3 3 3 3 2 8 9 IO IO II II 12 12 «3 *3 13 14 14 10 8 7 6 6 5 s S 4 4 4 4 10 7 8 9 IO IO 11 II ii 12 12 12 «3 18 >o <> 9 S 8 7 7 6 6 s S 15 6 7 7 8 8 9 IO IO IO 1 1 ti 20 11 IO IO 9 9 8 8 7 7 7 6 6 20 s 5 6 7 7 8 8 9 9 9 IO IO 25 12 I, IO IO 9 9 8 8 7 7 7 6 25 4 fi 6 6 7 7 8 8 9 9 9 IO 30 12 I I 1 1 IO IO 9 9 8 8 8 7 1 30 4 1 1 6 6 7 7 8 8 9 9 y 85 •3 12 ii IO IO o 9 9 8 8 7 7 sa 3 4 S 6 6 7 7 8 8 8 9 9 40 n 12 ii II IO IO 9 8 8 8 7 7 40 3 4 5 5 6 6 7 7 8 8 8 9 48 n 12 ii II IO IO IO 9 9 S 8 45 3 4 s s 6 6 7 7 7 8 8 8 50 »3 12 ii I! IO IO IO 9 9 9 9 8 60 3 4 5 5 6 6 7 7 8 8 8 60 11 12 12 II IO IO IO q 9 9 S 8 60 3 4 4 S S 6 6 7 7 7 8 8 70 n fl 12 11 II IO IO 9 9 9 s 8 70 2 3 4 s 5 6 6 6 7 7 8 8 80 »4 >3 12 I] II IO IO IO 9 9 8 8 80 2 3 4 4 5 5 6 6 7 7 7 8 When there are tewer than four figures ^n the Nat. Vers, make them up to four by adding ciphers : thus, in following example, Nat. vers. 258 becomes 2580 « 2b. 48m. 20s. Tab. (A), = Log. Vers. 4111 Tab. (0/. TABLES IS TABLES FOR FINDING Table (A) NAT.-VERSINES of M.Z.D. and Z.D. Time 20 40 1 20 40 2 20 40 3 20 40 4 20 40 5 20 40 Time. Arc 1 15 0150301)45 1 6 0) 42| 46 160 167 m m 3 4 m m 6 7 115 130!! 4.5 , 352 364 603 618 0371 956 1340)1302 18081834 2340i2368__. 2929129602991 U 3572 3606 3639 3673 4264 4300 •50005038 5774 5813 65806621 9931012 14061428 974 1384 __ 1859 1884J1910 2396|2424!2453 30223053 1372 5076 5114 5853 5893 6662 < 7496 741217454 8264 9128J91729215 7538 8393 Arc 10 30 50 1 10 30 50 2 10 30 50 3 10 I? 4 10 30 50 5 10 30 50 2 30 10 237 463 761 1130 m 245)3 12j 14 91! 97 247; 256 476i 489 778J 795 1 5011171 1566 1590; 1618 206GJ2093|2l20 •2627J265' 7 a ' iOC 3244 l 3276i3309 3912 i 3947j3982 4627j4664|470lJ4 5383io42l|546P fal •.'93 t 703=»i7076 3341'3374 4017 [4052 73814775 5499i5S38 31621416254 6294^335 ■"* 7118:7160 7836:787817921 8695I8738J8781 1882518868) 85 |9564j9607l9651 50 55| 59 175 184| 192 376; 387i 399 649j 664 680 |1031 1451 1936 2482 3707 4408 5152 5933 14741496,*,,. 1961198712014 :510 253912569 3085 31163148J3180 3741 3775 3809 3843 4444 4481I4517J4554 5190 usro 5228 5267 5305J5344 5973 6013 6053 609316133 6827 68688910 6951 67446786 7581 843C 7623 8479 ^259 93029340 7606 7708 775017793 S522|8565j8608|8651 9390943^9477 9520 315J330 345 I ■ " 161 19 21 103 110 116 266| 276]' 287 503[ 517i 531 812! 829] 847 U91|1212U233 1637il66ljl685 2147|2174;2201 2686 27l6j2746|27! 4087 4812 5577 F5376 7202 9695,9738,9762 64j 69 201 1 210 4121 424 696! 712 105111070 m m 8 9 20 215 6 75 219 437 728 1090 1520 PARTS. s s s s 1 4 8 1216202428 32364044 48 52 56 80 228 450 745 1110 1543 2040 2598 3212 3878 4590 I 8 4 0j4 15:4 30 4 45 24 27! 3l! 341 123| 1301 137j 144 297! 308j 319: 330 545j 559) 574' 588 865| 882 900: 919 1254|1275[l296jl8l8 1710!l734ll759ll784 2229 2256I22S4J2312 6|2807|2837 2867 f 2898 3407 34393472135063539 4122'4157!4193 4229 4850|4rt87|4925'4962 561g'5656|5695:5734 j6457|6498.6539 7244|7286|7328[7370 6876 6416 7964.8006 8049 8092 818981788221 8911|8955]8998j9042l908e 9826|9669l9913!995G Tabic (B) LOG-SECANTS of LAT. and PEC. De* 0' 6 10 15 25 30 35 40 0,6 15)030 045J1 0115 18 20 17, 68| 70j 73 16li 156' 101 2-io 277! 284 427j 436 445 625! 636' 647 866 880! 893 1157117811190 45 1505 1524J1543 50 1919!l942ll966 55 12414.2441 2469 }2496 81 8 171] 17 166 291! 298; 306 454 468 473 65$' 6691 681 907) 020! 934 1206 122211239 1563! ! 562 It 1968,3011 2035j2068| [2524j255a 2581 1301452 6,215 1 2' 3' 30! 32 36 J 88j 92j 96j 106 188 188 194! 200 313' 3211 828! 336 482] 492! TSOij 511 692i 7G4J at* 728 948; 962} 977 1 991 1255:1272112891306 02 1622il642|l662jl683 2082j2107|2131 2610 26392668 iia 1 1 1 2 1 3 1 8 1 5 2 6 2 6 2 s s 1 4 il2 3 4 5 1 2 2 2 3 3 4 4 5 1 2 6 8 11 12 14 6 8 10|12 18 15 9 9110 6 8 1013 7 9 11 7 10 12 15 8 10 13 15 18 20 23 26 28 31 8 11 13 19 21 8 11 14117 19 22 8 11 14 9 11 14 9 12 1 4 5 6 7 8 2 21 4 11 11 13 14 15 8 9 10112 13 14 15 17 18 1214 15 17 16 18 17 19122 16 24 27 25 23 20 20 2 23 05 28 31 26 29 3 17 20 23 26 29 3 121620 2428 3238 4044 6 7 8 91011 1 l 3 3 5 6 7 8 9 11 11 910 15 17 15 17 19 17 19 123 19 21 2 20 2: 24 26 23 25 •::>o 33 36 35 37 36 39 H 37 40 37 40 35 38 41 9 1011 12 13 14 l 1 4 4 7 7 18 20 21 21 22 24 25 27 27 29 29 32 as si 34 4852 56 12 13 14 PARTS. 12 1 1 * I 1 1 1 2 1 2 2 12 3 1 4 13 5 2 3 5 2 4 3 4 5 1 2 a 21 8 4 8 3 3 4 4 1 5 7 5 6 8 6 6 911 6 7 8 1 1 2] 2 3 4i 4 4 6 8 8 9 1011 ft 4 6 7 8 9110 11 12 9 11 11 13 13 1 10 11 4 4 fi 5 6 7 13 13 1511 £ 16 17 19 2123 12 13 14 2 2 2 8 4 5 5 6 7 8 9 10 11 12 13 14 16 17 18 31 2 25 2 19 THE TIME AT SEA. 20 Ta zU: >). MERIDIAN ZENITH-DiSTANCE. ALT. 0° 1° 2° | 3° ! 4° 5° 6° r \ 8° | 9° 10° 11° Alt. 8 7 8 3604 EM503 9601 9597 9592 j 9586 9578 9568 9557 9545 9531 | 9516 5° 32 1520 9518 9514 i 9509 9502 9494 9484 9473 9460 9446 j 9430 G 943t 9485 9433 9429 9424 9417 9403 9399 9SS7 9374 9360 9344 7 934;. U8 9346 9343 9337 9330 9321 9311 9300 9287 9272 9255 8 926" £60 9258 9?.54 9249 9242 9233 9223 9211 9197 . 9182 9166 9 10 li 12 13 14 9172 ^171 9168 9164 9159 9152 9143 9132 9120 9106 9091 i 9074 10 908' 9079 9077 3D73 90G7 9060 9051 9040 9028 9014 8998 89B1 11 39GS -987 8984 8980 8974 8967 8958 8947 8934 8920 8904 68S6 12 889S 8892 B890 8836 8880 8872 8862 8851 8838 8824 8807 87S9 1.3 8797 j B796 8794 8789 8783 8775 8786 8754 8741 8726 8709 8691 14 15 16 17 18 19 869U 1 8598 869G 8891 8685 8677 8667 8655 8842 8626 8809 8590 15 860>J> J 8599 8596 8591 8585 8577 8567 8555 8541 8525 8507 1 8488 16 8498 j 8 497 8494 8490 S483 8475 8464 8452 8438 8422 8404 8384 17 8395 1 8S94 8391 8386 8379 8371 8380 8348 8333 8317 8298 8278 18 8283 8288 8285 8280 8274 8265 8254 8241 8226 8209 8190 8169 19 20 21 22 23 24 8182 8181 8178 8173 8166 8157 8146 8133 8117 8100 8081 | 8059 20 8073 8072 8069 8064 8056 8047 8038 8022 8006 7989 7969 1 7947 21 7961 7960 7957 7952 7945 7935 7923 7909 7393 7875 7855 7832 22 7848 7847 7844 7838 7981 7821 7809 7795 7778 7759 7738 7715 23 7732 7731 7728 7722 7715 7705 7692 7678 7661 7641 7820 7596 24 25 26 27 23 29 7615 7612 7610 7604. 759(5 7586 7573 7558 7541 7521 7499 | 7474 25 7495 7493 7490 7484 7476 7465 7452 7437 7419 7398 7375 7350 26 7372 7371 7367 7381 7»53 7342 7328 7312 7294 7273 7249 7223 27 7247 7246 7242 7236 7227 7216 7202 7186 7167 7145 7121 7094 28 7120 7118 7115 7108 7099 7087 707? 7056 7037 7015 6990 6982 29 30 31 32 33 34 6990 5998 6984 6978 6968 6956 6942 6924 6904 6881 6856 6827 30 6857 6856 6852 5845 6835 6823 6808 6790 6769 6745 6719 6689 31 6722 6720 6716 6709 6699 6686 667? 6852 6631 6607 6579 6549 32 6584 6582 6578 6570 6560 6547 6531 6512 6490 6464 6436 6405 33 6443 6441 6436 6429 6418 6405 6388 6368 6345 6319 6290 6258 34 35 36 37 38 39 6298 6297 6292 6284 6274 6259 6242 6222 6198 6171 6141 6107 35 6151 6150 6145 6137 8126 6111 6093 6072 6047 6020 5988 5953 IS 6001 5999 5994 5986 5974 5959 5941 5919 5893 5864 5832 5796 37 5847 5845 5840 5832 5820 5804 S785 5762 5736 5706 5672 5634 38 5690 5688 5683 5674 5661 5645 5625 5602 5574 5543 5508 5469 39 40 41 42 43 44 5529 5527 5522 5513 5500 5483 5462 5438 5409 5377 5341 5300 40 5365 5363 5357 5348 5334 5317 5295 5270 5240 5207 5169 5126 41 5197 ! 5195 5189 5179 5164 5146 5124 5098 | 5067 5032 4992 4948 42 5024 5022 5018 5006 4991 4972 4949 4921 4889 4853 4812 4766 43 4848 4846 4839 4828 4813 4793 4769 4741 j 4707 4669 4626 4578 44 45 46 47 48 49 4667 4665 4658 4647 4631 4610 4585 4555 4520 4481 4436 4386 45 4482 4479 4472 4461 4444 4423 4396 4365 4329 4287 4240 4138 46 4292 4289 4282 4270 4252 4230 4202 4170 4132 4088 4039 3984 47 4097 4094 4087 4074 4056 4032 4003 3969 3929 S883 3832 S775 48 3897 3894 3886 3872 3853 3829 3799 3763 3721 3673 3619 3559 49 50 51 52 53 54 3691 3688 3680 3666 3646 3620 3588 3551 3507 3457 3400 3336 50 3480 3477 3468 3453 3433 3405 3372 3332 3286 3233 3174 3107 51 8263 3260 3251 3235 3213 3184 3149 3108 3059 3003 2940 2869 52 3040 3036 3027 3010 2987 2957 2920 2876 2825 2766 2699 2C24 53 2810 2806 2796 2779 2754 2723 2683 2637 2583 2520 2450 2371 54 55 56 57 58 59 2573 2570 2559 2540 2514 2481 2440 2390 2333 2267 2192 2108 55 2329 2325 2313 2294 2267 2231 2188 2135 2074 2004 1925 1835 56 2077 2073 2061 2040 2011 1973 1927 1872 1807 1732 1648 1552 57 1817 1813 1800 1778 1747 1707 1658 1599 1530 1460 J860 1257 58 1548 1544 1530 1506 1474 1431 1378 1316 1242 1157 1060 0950 59 60 61 62 6< 1270 1265 1250 1226 1191 1145 1089 1022 0943 0851 0747 9630 60 0982 0977 0961 0935 0897 0848 0788 0716 0631 0583 0421 0294 61 0684 0678 0661 0633 0592 0540 0476 0398 0307 0201 0080 9942 62 0374 0368 0350 0319 0276 0220 0150 0066 9968 9853 9722 9572 63 64 0052 0046 0026 9993 9940 9886 9810 9720 9613 9489 9846 9182 01 2J Table (D) MERIDIAN ZENITH-DISTANCE. Alt 12° | 13 c 14° 15° 16° 1? o 18° 19° 20° 21° 22° 23° JAxt. 5 C 9499 9480 9460 9439 9416 9391 9365 9337 9307 9276 9243 9208 5° 6 9413 9394 9374 9352 9328 9303 9276 9248 9218 9186 9152 9117 Q 7 9326 9307 9286 9264 9240 [ 9214 9187 9157 9127 9094 9060 9024 7 8 9237 9218 9197 9174 9149 ! 9123 9095 9065 9034 9000 8965 8928 8 9 9 9147 9127 9106 9082 9057 9030 9002 89Z1 8939 8905 8869 8831 10 9055 9035 9013 8989 8963 i 8936 8906 8875 3843 8808 | 8771 8732 10 11 11 896-2 8941 j 8918 8894 8867 : 8839 8810 8778 8744 8709 8671 3631 12 8866 8845 8822 8797 8770 | 8741 8711 8678 8644 8607 : 8569 8528 12 13 8769 8747 8724 8698 8671 ' 8641 8610 8577 8541 3504 ; 8465 .8423 13 14 14 8670 8648< 8624 8597 8569 8539 S507 8473 8437 8399 , 8359 8316 15 35C9 8546 8522 8495 8466 j 84S5 8403 8368 8S31 8291 i 8250 8207 15 16 8467 8443 8418 8390 8361 ; 8329 8296 8260 8222 8182 8139 8095 18 17 8362 8338 8312 8284 8254 | 822.1. 8187 8150 8111 8070 8028 7981 3? 18 8255 8230 8204 8175 3144 8111 8076 8038 75*98 7956 1 7911 7864 18 19 19 8146 8121 8094 8064 I 8032 j 7999 7962 7924 7883 7839 : 7793 7745 20 8085 8010 7981 7951 ! 7919 ! 7884 784'1 7807- 7765 7720 ] 7673 7623 20 2] 21 7922 ! 7896 7867 7836 7802 ! 7787 7728 1 7687 ! 7644 7598 I 7550 7498 22 7807 7780 7750 7718 7684 7647 7608 1 7566 ! 7521, 7474 I 7424 7371 2? 23 7689 7661 7631 7598 7563 ! 7525 7484 ! 7441 j 7395 7347 7295 7241 23 24 24 7569 7541, 7509 7476 7439 7400 7359 7314 j 7267 7217 j 7164 7108 25 7447 7417 7385 7350 7313 7273 7230 7184 i 7185 7084 ! 7029 «971 25 26 2? 28 29 26 7322 7292 7259 7223 7184 7143 •7099 7051 ! 7001 6948 6891 6832 27 7195 7163 7129 7092 7052 i 7010 6964 6915 8864 6399 ! 6750 668S- ;>. 7064 7032 ! 6997 6959 6918 ; 6874 6827 8777 6723 6666 j 6606 6542 29 6931 6898 j 6862 6823 6780 I 6735 6686 66£4 8579 6520 6458 0S92 30 6796 6761 6724 6683 6640 6593 6542 6489 6432 6371 6806 8238 30 31 32 33 34 31 6657 6621 6583 6541 6495 6447 6395 6340 8280 6217 j 6150 'j080 32 6515 6478 1 6438 8395 6348 6298 6244 6187 6125 6060 5991 5917 33 6370 6332 j 6291 6246 6197 6145 6090 6030 5967 5899 5827 5750 34 -6222 6182 6139 | 6093 6043 5989 5931 5870 5804 5783 j 5658 5579 35 6070 6029 5985 5937 5885 5829 5769 6705 5686 1 5563 5485 5402 35 38 37 38 39 3$ 5915 5872 I 5826 5777 5723 ! 5665 5602 5536 5464 5388 5S07 5221 37 5756 5712 5664 5612 5556 ! 5496 5431 5362 5288 5208 5124 50S4 38 5593 5547 f 5498 5444 [ 5386 j 5323 5256 5183 5106 5023 4S35 4841 39 5426 5379 5327 5271 i 5211 5145 ] 5075 5000 4919 4882 4740 4642 40 5255 5206 ; 5152 5094 5031 4963 4889 48H 4726 4636 4539 4436 40 41 42 43 44 41 5080 J 5029 4973 4912 I 4846 ; 4775 4698 4616 4528 4433 : 4832 4223 42 4900 ' 4846 ! 47R8 4725 | 4656 4581 4501 4415 4323 4223 ! 4117 4( ■:'. 43 47 5 ' 4659 4598 4532 I 4460 4382 4298 4208 4111 4007 ; 8895 3775 44 4525 j 4467 | 4403 4334 4259 4177 4089 3994 3892 8783 3665 8538 45 4380 4269 4203 4130 4051 3965 3873 3773 3666 3559 3426 5292 45 48 47 48 49 46 4130 4066 ! 3996 3920 .3837 3747 3650 3545 3431 8309 j 3177 3036 47 3 923 3856 : 3783 3703 3615 3521 3418 3307 3188 3058 2919 27 ' 18 3710 3640 3563 3479 3387 3287 3179 3062 2935 2797 | 2649 248S 49 8492 3418 3336 3247 ! 3150 j 3045 2930 2806 2671 2525 2367 2i96 50 3265 | 3187 ' 3102 3008 ■ 2905 2793 2672 2fi0 2397 2241 2072 1 1888 50 51 52 53 54 si 3032 2950 2859 2760 ! 2651 i 2532 2403 2263 2110 1943 1762 -: 5« t 52 2791 2703 ' 2607 2502 ,2387 j 2261 2123 i 1973 1809 1631 1436 1222 2541 j 2448 i 2347 2235 j 2112 ' 1978 1830 j 1670 j 1494 1301 1091 1 0859 54 2282 ' 2184 | 2076 i 1956 1825 1682 1524 1351 ! 1162 0954 , 0725 j 0472 55 2014 ; 3909 1794 1666 ; 1526 1372 1203 1016 0811 0585 ! 0336 i 00 i8 I 58 59 56 1735 : 1624 1500 1364 ! 1213 1047 0864 066? 0440 0198 ! 9919 i 9813 57 1445 ( 1326 1193 1047 i 0885 0705 0507 02sri 0044 9773 j 9470 9129 58 1143 1015 0872 0714 | 0539 0345 0129 9889 9621 9321 j 8984 8601 59 0827 0689 0536 0365 0174 9962 9726 9462 9166 8832 8153 8017 60 0497 0348 ! 0182 9996 9788 9556 9296 9003 8673 8297 7865 7362 60 61 62 63 64 61 0151 9989 i 9808 9605 9377 9121 8886 8503 8134 7706 7207 6617 62 9786 9611 9413 9190 8938 8654 8332 7964 7539 7044 6458 5747 63 y«ra 64 3996 9210 8992 j 8467 j 8467 8149 7785 7365 6874 6291 fi .--■' 8784 8543 | 8269 1 7957 7598 7182 6695 6117 5414 1 Table (D). MERIDIAN ZENITH-DISTANCE. AlTw 24° 25° 26° 9094 27° 28° 29° 30° 31° 32° 33° 34° 35° Alt. 5° 9172 9134 9052 9008 8962 8915 8865 8813 8759 i 8703 8645 5 6 9080 9041 9000 8957 8912 8865 8817 8766 8713 8658 8600 8541 6 7 8986 8946 8904 8860 8814 8767 8717 8665 8610 8554 i 8495 8434 7 8 8889 8840 8806 8761 8714 8666 8614 8561 8506 8448 8388 8325 8 9 8792 8750 8706 8660 8612 8562 8310 8456 8399 8339 8278 8213 9 10 8692 8649 8604 8557 8508 8457 8403 8348 8289 8228 | 8165 8099 10 11 8590 8546 8500 8452 8402 8349 8294 8237 8177 8115 j 8050 7982 11 12 8486 8441 8394 8344 8293 8239 8183 8124 8063 7999 ! 7932 7862 12 13 8380 8334 8286 8235 8182 8127 8069 8009 7946 7880 i 7811 7739 13 14 8271 8224 8175 8123 8069 8012 7953 7890 7826 7758 7687 7613 14 15 8161 8112 8062 8008 7953 7894 7833 7770 7703 7633 j 7560 7485 15 16 8048 7998 7946 7891 7834 7774 7711 7646 7577 7505 1 7430 7352 16 17 7932 7881 7828 7772 7713 7651 7586 7519 7448 7374 | 7297 7216 17 18 7814 7762 7707 7649 7589 7525 7459 7389 7316 7240 • 7160 7077 18 19 7694 7640 7583 7524 7461 7396 7328 7256 7181 7102 7020 6934 19 20 7570 7515 7457 7396 7331 7264 7193 7119 7042 6961 6875 6786 20 21 7444 7387 7327 7264 7198 7129 7056 6979 6899 6815 6727 6635 21 22 7315 7257 7195 7130 7062 6990 6915 6836 6753 6666 6575 6479 22 23 7183 7123 7059 6992 6922 6847 6770 6688 6602 6512 64 IS 6319 23 24 7048 6986 6920 6851 6778 6701 6621 6536 6447 6354 6256 6153 24 25 6910 6846 6778 6706 6631 6551 6468 6380 6288 6191 6090 5983 25 26 6768 6702 6632 6558 6479 6397 6311 6220 6124 6024 J 5918 5807 26 27 6623 6554 6482 6405 6324 6239 6149 6055 5956 5851 5741 5625 27 28 6475 6403 6328 6248 6365 6076 59S3 5885 5782 5673 5558 5437 28 29 6322 6248 6170 6087 6000 5909 5812 5710 5602 5488 5368 5242 29 30 6165 6089 6007 5922 5831 5736 5635 5529 5416 5298 5172 5040 30 31 6004 5925 5841 5752 5657 5558 5453 5342 5225 5101 4969 4830 31 32 5839 5756 5669 5576 5478 5374 5265 5149 5026 4896 4758 4612 32 33 5669 5583 5492 5395 5293 5185 5070 4949 4820 4684 4539 4386 33 34 5494 5405 5310 5209 5102 4989 4869 4742 4607 4463 4311 4149 34 35 5314 5221 5122 5016 4905 4786 4660 4527 4385 4234 4073 3902 35 36 5129 5031 4928 4817 4701 4576 4444 4304 4154 3995 3825 3648 36 37 4938 4836 4727 4612 4489 4359 4219 4071 3913 3745 3564 3371 37 38 4740 4634 4520 4399 4270 4132 3986 3829 3662 3483 3292 3085 33 39 4537 4425 4305 4178 4042 3897 3742 3576 3399 3209 3004 2784 39 40 4326 4208 4082 3948 3805 3652 3488 3312 3123 2920 2701 2464 40 41 410.8 3984 3851 3710 3558 3396 3222 3034 2833 2615 2380 2124 41 42 3881 3751 3611 3461 3300 3128 2942 2742 2527 2293 2039 1761 42 43 3646 3508 3361 3202 3031 2847 2649 2435 2202 19.30 1674 1372 43 44 3402 3256 3099 2930 2748 2552 2339 2109 1858 1584 1283 0952 44 45 3148 2993 2826 2646 2453 2240 2012 1763 1490 1191 0861 0494 45 46 2«83 2718 2539 2347 2138 1911 1664 1393 1096 0767 0402 9992 46 47 2605 2429 2239 2032 1807 ! 1561 1293 0997 0671 0307 9898 9435 47 48 2315 2126 1921 1699 1455 1 1188 0895 0570 0208 9801 9340 8809 48 49 2009 1807 1586 1345 1080 J 0789 0465 0105 9701 9241 8712 8092 49 50 1688 1469 1230 0968 0678 i 0357 9999 9596 9138 S611 7993 7252 50 51 J 348 1111 0851 0564 0245 9889 9488 9032 8507 7891 51 52 0988 0730 0445 0128 9774 9376 8922 8398 7784 7047 52 53 0604 0321 0007 9655 9259 8807 8286 7674 6938 6024 if 54 0192 9881 9c 32 9138 8688 8169 7559 6826 '5914 4721 55 9749 9403 9011 8565 8048 7440 6709 5800 4608 2905 55 56 9269 8880 8130 7922 7317 6588 56 57 8743 8302 7790 7188 6462 5557 57 58 8162 7654 7054 6331 5428 58 59 7611 6914 6194 5294 59 60 6769 6051 5155 ■ 60 61 5902 1 61 23 Table (D). MERIDIAN ZENITH-DISTANCE. Alt 36° 37° 38° 39° 40° 41° 42° 43° 44° 45° 46° 47° Alt. 5 C 8585 8522 8456 8388 8318 8245 8169 8090 8008 7924 7835 7744 5° 6 8479 8414 8347 8278 8205 8130 8052 7972 7887 7800 7709 7615 6 7 8371 8304 8236 8164 8090 8013 7933 7850 7.63 7673 7580 7483 7 8 8260 8192 8121 8048 7972 7893 7810 7725 7636 7543 744T 7347 8 9 8146 8077 8004 7929 7851 7769 7684 7596 7504 7409 7310 7206 9 10 8030 7959 7884 7807 7726 7642 7555 7464 7369 7271 7168 7062 10 11 7911 7838 7761 7681 7599 7512 7422 7328 7231 7129 7023 6912 11 12 7789 7714 7635 7553 7467 7378 7285 7189 7088 6983 6873 6759 12 13 7665 7587 7508 7421 7333 7241 7145 7045 6941 6832 6718 6600 13 14 7537 7456 7373 7285 7194 7099 7000 6897 6789 6676 6558 6435 14 15 7405 7322 7236 7146 7052 6954 6851 6744 6632 6516 6393 6265 15 16 7270 7185 7096 7003 6906 6804 6698 6587 6471 6350 6222 6089 16 17 7132 7044 6952 6855 6755 6650 6540 6425 6304 6178 6045 5907 17 18 6990 6899 6803 6704 6599 6490 6376 6257 6131 6000 5862 5717 18 19 684.4 6749 6651 6547 6439 6326 6207 6083 5952 5815 5671 5520 19 20 6693 6596 6493 6386 6274 6156 6033 5903 5767 5624 5473 5315 20 21 6538 6437 6331 6220 6103 5981 5852 5717 5575 5425 5267 5100 21 22 6379 6274 6164 6048 5927 5799 5665 5524 5375 5218 5052 4877 22 23 6215 6106 5991 5870 5744 S611 5470 5323 5167 5002 4828 4643 23 24 0045 5932 5812 5687 5555 5415 5269 5114 4950 4777 4593 4397 24 25 5870 5752 5628 5497 5358 5213 5059 4896 4723 4541 4346 4139 25 26 88 5690 5566 5436 5299 5154 5002 4840" 4668 4487 4'293 4087 8867 27 5502 3374 5238 5094 4942 4782 4611 4430 4238 4033 3814 3580 27 28 5309 5174 5032 4881 4721 4552 4372 4181 3977 3759 3525 8274 23 29 5108 4967 4817 4659 4491 4312 4122 3919 3702 3469 3219 2949 29 !?' 4900l 4751 j 4594 4427 4249 4060 3859 3648 3411 3162 2893 2601 30 4683 4527 4361 4185 3997 8796 3581 3351 3103 2835 2544 2226 31 32 4458 4293 4118 3931 3731 3518 3288 3041 2774 2484 2168 1821 32 32 4222 4018 3863 3664 3452 3224 2978 2712 2423 2108 1761 1379 33 34 3976 3792 3595 8384' 3157 2912 2.47 2359 2045 1700 1318 0892 34 35 3719 3523 i 3313 3087 2844 2580 2 293 1»81 1636 1256 0831 0351 35 36 3448 3240 3015 2773 2611 2225 1913 1571 1191 0767 0289 9741 36 37 3164 2941 2700 2439 2154 1844 1502 1124 0701 0224 9677 9041 37 3S 2864 2624 2364 2081 1772 1432 1055 0633 0157 9612 8976 8217 38 39 2545 2287 2006 1698 1359 0983 0562 0087 9543 8909 8152 30 40 2207 1927 1620 1283 1 0908 0489 0016 9473 8840 8083 ! 40 41 1646 1540 1204 0*JI ! 0413 9941 9399 8768 8013 41 42 1458 1123 0751 0335 1 9864 9324 8693 7940 42 43 1039 0668 0254 9784.' 9245 8616 7864 43 44 0593 0169 9701 9164 8536 7785 I 44 45 0032 9616 9080 8453 7704 j | 45 40 0527 8993 8368 7620 1 i 46 47 S9C2 «279 7533 I 47 49 81S7 7442 6520 ! 48 48 7349 j S428 1 49 50 6332 j 1 1 50 j 24 Table (D). MERIDIAN ZENITH-DISTANCE. Alt. 48° 49° | 50° 51° 52° 53° 54* 55° 56° 57° 58° 59° Alt. 5° 7649 7550. 7448 7341 7231 7115 6995 6870 6740 6604 6462 6313 5° 1 7517 i 7416 7310 7200 | 7085 6966 6842 6712 6577 6436 6288 6133 6 3 7382 | 7277 7168 7054 | 6935 6812 6883 6J49 6408 6281 6107 5946 7 8 7242 ! 7134 7021 6903 6781 6652 6519 1 6379 6233 080 5919 5750 8 S 7099 j 6986 6870 674S | 6620 6487 6348 j 6203 6050 5891 5723 5546 8 10 6950 6834 6712 658,7 j 6454 6316 6171 G020 5861 5694 5518 5332 10 11 6797 6677 6420 6282 6138 5983 5829 5688 5488 5303 5109 11 12 6689 6514 6384 6247 ! 6104 5954 5796 5631 5457 5273 5079 4878 12 ia ■ 6476 6346 8210 6068 j 5919 5762 5424 5341 5047 4843 4625 13 6306 <" 60S0 58S2 ! 5726 j 5562 5389 5207 5014 » 4777 4810 4594 4364 14 15 j 6131 18 i 5949 5991 5843 568S | 5525 5353 5171 49«0 4561 4331 4086 15 5803 5648 5486 5315 5135 4944 4741 4526 4298 4053 3791 16 17 j 5761 18 ' 5564 5607 5446 5276 5096 4900 4704 4490 4262 4019 3758 3477 17 5404 5235 5056 4866 4666 4452 4225 3988 3722 3442 3139 lb i9 5360 5192 5014 4825 4625 4413 4187 3945 8685 3406 3104 2775 19 1? 5147 4970 4782 4583 4372 4146 3905 3647 3067 2739 2381 20 4924 4738 4540 4329 4104 3864 3606 3829 3028 2701 2344 1950 21 52 4681 4494 4284 4060 3821 3564 3287 2988 2662 2305 1912 1475 22 23 4447 4238 4015 3776 3520 3245 2946 2621 2265 1873 1436 0945 23 24 4190 3968 3730 3475 3200 2'. >2 2578 2223 1831 1396 0905 0346 24 25 8918 3428 3163 2857 2533 2179 1789 1354 0864 0306 9658 25 28 3682 , -/S 3105 2809 2487 2) i 1744 1310 0821 0264 9616 8846 26 27 3827 065 2760 2439 2086 16i*7 1264 0777 0220 9574 8804 27 28 S003 2388 2037 1649 1217 ' 0175 9529 8760 28 29 2666 1986 1599 1168 0682 0127 9482 8715 29 30 2282 193S 1547 1117 0632 0078 9434 ! 167 30 33 1878 1493 1064 i;580 0027 9384 8618 31 3! 1487 1008 0526 9974 9332 81 ? 32 SS 0951 0470 9278 8514 33 34 M12 9862 9222 34 35 9803 9164 8402 35 38 : 9108 6343 36 37 ' 8283 J « 37 25 Table (D). MERIDIAN ZENITH-DISTANCE. kvp. 60° 61 62° 63 64- 65° 66° 67° 63° 69° 70° 1 71° SlLT. 5° 6 6158 599i> 5324 5645 5456 5256 5046 4823 4586 4333 4063 3773 5° 5971 5801 5622 5434 5235 5025 4803 4587 4315 4046 3756 3445 6 7 5776 5598 5411 5213 5004 4782 4546 4295 4027 8738 3427 3090 7 8 5573 ,5386 5189 4981 4760 4525 4274 4006 3719 8408 3072 2704 •8 9 5360 5164 4956 4736 4502 4252 3985 3698 3388 3052 2685 2282 9 10 11 5137 -±930 4710 4477 5228 3961 3675 3366 3031 2*65 2263 1816 10 4904 4683 4451 4203 3937 3651 3343 3009 2643 2242 1796 1296 11 12 4655 4423 4176 3911 3626 3318 2985 2C20 2219 1774 1275 0706 12 13 4394 4147 3883 3599 3292 2959 2596 2195 1751 1252 0685 0027 13 14 4118 3854 3571 S265 2933 2570 2170 1,20 1228 0661 0004 9224 1 14 15 8823 3,541 3236 2904 2542 &L43 1700 1203 0637 9980 9201 15 16 3509 3206 2874 2513 2115 1673 1176 0631 9955 9177 16 1? 3173 f - 13 2482 2085 1648 1148 0583 9928 9151 17 18 2810 i J450 2054 1813 1118 0554 9900 9123 j 18 13 2416 '2020 1581 1086 0523 9870 9094 19 20 1986 1547 1054 0191 9839 9063 20 21 1512 1019 j 0457 9806 9031 1 22 0983 0422 1 9771 8397 23 0385 9735 1 8882 23 24 9697 8925 1 24 25 8886 25 Table (D). M ERIDIAN ZENITH-DISTANCE. AiT. 72 p 73° 74° 7- 76° 77° 78° 78° 1 80 3 0156 9370 81 c 82° 1 83° 5° 5 3461 3122 2753 2347 1897 1392 0819 6 3107 2738 2333 1883 1S80 0807 0144 9i»59 6 7 2722 2317 1869 1266 0794 0182 9347 • 7 8 2300 1853 1550 0779 0118 9334 i 8 9 1835 I 1383 0763 0102 9319 9 10 1315 ! 0745 0086 9303 i 10 11 0727 | 0067 9285 i 11 12 0048 9267 12 13 9246 1 13 14 ! 14 Table (D). MULTIPLIERS FOR MINUTES OF ALTITUDE. MlN 0' r 2' 3' 4' 5' 6' 7' 8' 9' 10' •00 •02 • 03 ' •05 •07 • -08 10 •12 13 ♦16 •17 10 17 •18 20 •22 •23 1 -25 •27 •28 •30 .•82 •33 20 •33 •35 •37 •38 •40 1 '42 •43 •45 •47 •48 •50 30 •50 •52 •53 •55 •57 ' -58 •60 •62 •63 •65 •67 40 •67 •68 •70 •72 •74 -75 •77 •78 •80 •82 •83 50 •83 •85 •87 •88 •90 -92 •93. •95 •97 •98 J 00 ti c Ch 10 12 14 Table (E). LATITUDE. 6 4 8 lb 12 14 16 18 20 22 24 a 28 30 32 5-67 4-71 401 r 5-70 472 402 5-73 4-75 4-04 5-76 4-78 4-06 5-79 4-81 409 5-85 4-85 412 5-91 4-89 4-16 5-97 4-95 4-20 6J)3 501 4-26 6-12 508 4-32 6-21 5-16 4-38 6-30 5-28 446 6-42 5-34 4-54 6-55 5-43 4-63 6-69 5-55 4-73 16 18 20 3-49 3-08 2-75 3-50 3-09 2-76 3-52 311 2-78 3-54 313 2-79 3-56 315 2-81 3-59 3-18 2-83 3-62 3 20 2-86 3-66 3-24 2-89 3-70 3-28 2-92 3-76 3-32 2-96 3-82 3-37 301 3-88 3-43 3-06 3-94 3-49 312 4-02 3-55 3-17 4-11 3-63 3-24 22 24 26 2-47 2-25 205 2-47 2-26 2-05 2-48 2*27 207 2-50 2-28 208 2-52 2-30 210 2 54 2-32 211 2-57 2-34 2-13 2/60 2-37 2-15 2-63 2-39 2-18 2-66 2-43 2-21 2-70 2-46 2-24 2-75 2-50 228 2-80 2-55 2-32 2-86 2-59 2-37 2-92 265 2-42 28 30 32 1-88 1-73 160 1-88 1-73 1-60 1-90 1-75 1-62 1-91 1-76 1-63 1-92 1-77 1-64 1-94 1-78 1-65 1-96 1-80 1-66 1-98 1-82 1-68 200 1-84 1-70 203 1-87 1-73 2-06 1-89 1-75 2-09 1-92 1-78 2-18 1-96 1-81 2-17 2 00 1-83 2-22 2-04 1-89 S4 36 38 1-48 1-38 1-28 1-48 1-38 1-28 1-49 1-39 1-28 1-50 1-40 1-29 1-51 1-41 1-30 153 1-42 1-31 154 144 1-32 1-56 1-46 1-34 1-57 1-47 185 1-60 149 1-37 1-62 1-51 1-39 1-65 1-63 1-41 1-68 1-55 1-44 171 1-59 1-48 1-75 1-62 1-51 40 42 44 119 111 104; 1-19 111 104 1-20 1-12 1-04 1-21 113 105 1-22 1*14 10G 1-23 114 107 124 115 108 1-25 1-17 1-09 1-27 1-18 1-10 1-28 1-20 1-12 1-30 1-22 113 1-32 1-24 1-15 1-35 1-26 M7 1-38 1-28 1-20 141 1-31 1-22 46 4.8 50 0-97 0-90 0-84 0-97 0-90 0'84 0-98 0-91 0-85 0-98 0-91 85 0-99 0-92 086 100 93 0-87 1-01 0-94 0-87 1-02 0-95 0'88 1-03 0-96 0-89 1-04 0-97 0-91 106 0-99 0-92 1-07 1-00 93 109 1-02 0-95 111 104 97 1-14 1-06 0-99 52 54 56 0-78 73 0-67 0-78 073 0-67 0-79 0-73 0-68 79 0-74 068 0-80 0-74 0-69 80 075 0-69 81 1 0-82 75 I 0-76 0-70 | 0-71 0-83 0-77 0.71 0-84 78 0-72 0-85 0-79 0-73 0-87 81 0-75 088 0-82 0-77 090 84 0-78 0-92 0-86 0-79 58 80 62 063 0-68 053 063 0-58 053 063 0-59 0-54 0-03 059 0-54 0-64 0-59 0-54 064 0-60 055 0-65 0-60 055 0-66 0-61 0-56 0-66 0-62 056 0-67 0-62 057 0-68 0-63 0-68 0-89 065 0-59 0-71 0-66 0-60 72 067 0-61 0-74 0-68 0-63 64 68 88 0-49 0-45 040 0-49 0-45 40 0-60 0-43 0-40 0-50 0-45 0-41 0-50 0-46 0-41 0-51 0-46 041 0-51 046 042 0-52 0-47 042 0-52 0-47 0-43 0-53 0-48 0-43 0-54 0-49 0-44 0-55 0-50 0-45 0-56 0-50 45 0-56 0-51 0-47 0'57 0-52 0-47 70 72 74 038 0-33 0-29 0-36 0-33 0-29 0-88 0-33 0-29 0-37 0-33 0-29 0-37 034 0-30 0-37 0-34 0-30 0-37 0-84 30 088 0-34 0-31 38 0-35 031 0-39 035 0-31 039 0-36 0-32 .0-40 036 032 0-41 0-37 0*33 0-42 0-37 0-33 0-43 0-38 0-84 76 78 80 025 21 018 0-25 0-21 018 0-25 0-91 018 0-25 0-21 018 0-25 0-21 0-18 0-26 0-2-2 018 0-27 22 018 0-27 0-22 018 0-27 22 0-19 0-27 0-23 019 0-27 23 019 0-28 0-23 0-20 0-28 0-23 20 029 024 020 0-29 0-25 0-21 82 84 86 014 010 007 0-14 0-10 007 014 010 007 014 10 007 0-14 0-10 0-07 014 010 0-07 0-14 Oil 07 015 0-11 007 0-15 Oil 008 0-15 0-11 0-08 015 Oil 008 015 Oil 0-08 015 0-11 008 016 0*12 G'08 017 012 0'08 88 89 90 003 0-01 000 003 001 00 003 001 000 0-04 0-02 000 004 02 00 004 0-02 000 04 002 000 0-04 002 000 004 002 000 0-04 0-02 0-00 004 004 0'02 000 004 002 000 0-04 002 000 004 002 000 002 000 27 Table (E). LATITUDE. K '*j c 1 o 10 12 14 2 *i* 1 c ( ,.| . o n 34 36 38 40 1 42 . 44 46 48 50 52 54 58 58 60 3 li 6-84 5-67 4-84 7-01 5-81 4-95 7-20 5-97 5-09 7-40 6-14 5-23 7-63 6-33 5-40 1 7-88 6-54 5-58 816 6-77 6-77 8-48 7-03 5-99 8-82 732 6-24 921 7K54 6-51 9 65 800 682 1014 8-41 717 1070 8-88 7-57 11-33 9-41 8-02 5-76 4-70 413 16 18 20 4-21 371 8-31 4-31 3-80 3-39 4-43 3-90 3-49 4-55- 4-02 359 4-69 4-14 3-70 4-85 4-28 3-82 502 4-43 3-95 5-21 4-60 411 5-42 4-79 4-27 5-66 500 4-46 593 5-24 4-67 6-24 5-50 4-91 6-58 581 6-19 6-97 615 5--49 3 63 3-24 2-92 22 24 26 2-98 271 2-47 3-06 2-77 253 3-14 2-85 2-60 3-23 2-93 268 3-33 ?-02 in 3-44 3-12 2-85 3-56 3-23 2-95 3-70 3-36 3-06 3-85 3-49 3-19 4-02 3-65 3-33 421 382 349 4-43 402 3-66 4-67 4-24 "3-87 4-95 4-49 410 2-67 2-46 2-28. 23 30 32 2-27 209 1-93 2-32 214 198 2-39 220 2 03 2-45 2-26 2-09 2-53 2-33 215 2-61 2-41 2-22 2-71 2-49 280 2-81 2-60 2-39 2-92 2-69 2-49 305 2-81 2-60 3 20 2-95 2-72 3-36 3-10 2-86 3-55 3-27 3-02 3. 70 3-46 320 213 2 00 1-89 34 36 38 1-79 166 1-54 1-83 1-70 1-58 1-88 1-74 1-62 1-93 1-80 1-67 1-99 1-85 1-72 2-06 1-91 1-78 213 1-98 1-84 2-22 206 1-91 2-31 214 1-99 2-41 224 2-08 2-52 2-34 218 2-65 2-46 2-29 2-80 2-60 2-41 2-96 2-75 2-56 1-79 1-70 1-62 40 42 44 1-44 1-34 1-25 1-47 1-37 1-28 1-51 1-41 1-31 1-55 1-45 1-35 1-60 1-49 1-39 1-66 1-54 1-44 1-72 1-60 1-49 1-78 1-66 1-55 1-85 1-73 1-61 1-94 1-80 1-68 2-03 1-89 1-76 213 1-99 1-85 2-25 2-09 1-95 2-38. 2-22. 207 1-56 1-49 1-44 46 48 50 1-16 109 101 1-19 111 104 123 1-14 106 1-26 1-17 109 1-30 1-21 1-13 1-84 1-25 1-16 1-39 1«30 1-21 1-44 1-35 1-25 1-50 1-40 1-31 1-56 1-46 1-36 1-64 1-53 1-43 1-73 1-61 1-50 1-8-2 1-70 1-58 1.93 1-80 1-68 1-89 1-35 131 52 54 56 0-94 0-88 0-81 0-96 0-90 0-83 0-99 092 085 101 0-95 0-88 1-05 0-98 0-91 1-09 1-01 0-94 1-12 1-04 0-97 1-17 109 101 1-22 1-13 1-05 1-27 1*18 1-10 133 1-23 115 1-4Q 1-30 1«21 1-47 1-37 1-27 1-56 1:45 1-35 1-27 3-24 121 58 60 62 0.75 0-70 0-64 0-77 0-71 0-6G 0-79 0-73 0-67 81 ! 84 0-75 078 069 0-72 0-87 0-80 74 090 0-88 0-76 0-93 0-86 0-79 0-97 0-90 0-83 1-01 094 0-86 108 0-98 090 112 1-03 095 1-18 1-09 1-00 1-25 1-15 1-06 1-18 115 1-13 64 68 63 59 54 0-49 60 55 50 062 056 051 64 ' 0-66 058 ; 0-60 53 ! 0-54 0-68 0-62 0-56 0-70 0-64 0-58 0-73 0-66 0-60 0>76 0-69 0-63 0-79 0-72 0-65 083 0-76 0-69 0-87 073 0-72 0-92 84 0-76 0-97 0-89 0-81 111 109 1-08 70 72 74 044 0-39 0-oi 0-45 0-40 03b 046 0-41 0-36 0-47 0-42 37 0-49 0-44 038 0-51 0-45 040 0-52 047 41 0-54 0-49 043 0-57 051 0'44 0-59 053 0-46 0-62 55 0-49 65 0-53 52 0-68 0-61 0-54 073 065 057 1-06 1-05 104 76 78 80 0-30 0-25 21 31 26 022 031 0-27 22 0-32 0-28| 0-23 0-33 0-29 024 0-34 029 0-24 086 0-30 025 037 32 0-26 039 33 027 0*0 34 29 42 03f- 30 45 33 0-31 047 0-40 33 050 42 0-35 1-03 102 102 82 84 86 17 On 008 017 18 008 018 013 009 18 i 19 14 ! 14 09 : 009 019 14 10 0-20 015 010 0-21 016 0-10 022 0-16 Oil 23 017 Oil 24 18 12 0-25 19 12 0-20 20 013 0-23 21 014 1-01 1-01 VOO 88 89 90 001 02 09 04 002 00 001 02 o a«: 04 ' 05 02 1 02 00' 00 005 0.02 000 005 02 000 05 003 00 05 003 0-00 06 003 000 0-06 ooe 00 06 004 000 0-07 oos 000 07 0-5 ooo 100 100 100 1 1 1 1 1 MOTES. I. — If it be de.sired to take more than one altitude iu the maimer directed on page 5, set the sextant first at 30° -11', and secondly at BO" +11', when the Mean of the two will be SO , as requi.ed. This- applies to a.m. sights : For p.m. we must begin with ihe greatest altitude and proceed in like manner. To take four altitudes, set the sextant at 30° - 22', 30° - 11', 30° + 11' and 30° + 22', for A.M. sights; and in the. reverse order for P.M. observations II-— Application of Tables A, B, G, to finding the^ Altitude Azimuth, (a) Lai. and Dec. of same name : Take difference of lat. and alt. (b) Lat. and Dec. of contrary names : Take sum of lat and alt. For North declination, take N.P.D. and reckon Azimuth from North. For South declination, take S.P.D. and reckon Azimuth from South, and proceed as in finding the time. Example I., a.m. Example II., p.m. L it. 23° 45' N., Alt. 21° 42', Dec. 20° 49' N. Lat. 23° 45' N. 384 Lat. 25° 31 N. 446 Tab. A. Alt. 21 42 6 Diff. 6446 N.P.D. >49'N. 384 319 Lat. 25° Tab. A. 31 'N.Dec. 14° 47' S, Alt.] 5 C Lat. 25° 31 N. Alt. 15 46 2486 7449 4963 Sum 41 17 S.P.D. 75 13 8090 3h. 59m. 2s. 8793 *4h. 18m 30s. 6440 4h. 36m. 36s. *5h. 3m. 48s. 8793 *4h. 18m HOs. 7570 .-. Az. = N. 75* 57' E. .-. Az. = S. 64' fty W. When the Azimuth exceeds the limit of Table (B), which it can only do when latitude and declination are of the same name, substract the sum of lat. and alt. from 180^, and proceed as before, marking the Azimuth with the contrary name to the declination. III. — To find the time of sunset and sunrise by the same Tables ; proceed as in the following Examples : 74 372 9187 Tab. A. Lat. Dec. 1706 10000 M.Z. Z.D. 8294 5h. Sunset Sunrise 5 6 10° 35' N. 23 23 S. 33 58 90 20m . 41s. 41 18 24 p.m. 36 A.M. 9633 IV.— To find the Azimuth at rising or setting, make the Altitude 0°, and proceed as in Examples I and II. above, » Thus 5h. 3m. 48s. = 303m. 48s., wnich divided by 4 75? 57' ; and 4h. 18m. 30s. = 258m. 30s., which divided by 4 - 64* 37^'- LIST OF NAUTICAL WORKS PUBLISHED BY J. D. POTTER. 145, MINORIES, LONDOK E. 1 LIST OF NAUTICAL WORKS Published by J. D. Potter. ALTITUDE TABLES. s. a. Computed for Intervals of Four Minutes between the Parallels of Latitude 31' and 60° and Parallels of Declination 0° and 24°, designed for the Determination of the Poiition Line at all Hour Angles without Logarithmic Computation, by Frederick Ball, M.A. (late Scholar of Exeter College, Oxford), Chaplain and Naval Instructor in Eis Majesty's Fleet ... ... ... ... ... ... ... ... 18 Ditto, ditto, between the Parallels of Latitude 0" and 30" and Parallels of Declination 0° and 24° 18 Ditto, ditto, between the Parallels of Latitude 24° and 60° and Parallels of Declination 24° and 60° 18 These Tables are so arranged for working by the Neiv Navigation that only one correction has to be applied to the altitude taken direct from the book. The entire lo garithmic work is replaced by a single subtraction and the application of the correct ion. In conjunction with the Nautical Almanac all the usual problems of Navigation are solved. The Tables have been adopted for use in the Japanese Navy. Altitude and Azimuth Tables, for Facilitating the Determination of Lines of Position and Geographical Position at Sea. The simplest and readiest in solution. Plane and Spherical Traverse Tables for solving all problems of navigation. By Lieut. Radler de Aquino (Brazilian Navy). All sights for position are worked out by the same method ivithout logarithms, with haidly any calculation. All the other problems in navigation are easily and rapidly solved by inspection without in- terpolation. This work has received the favourable endorsement of the United States Ej drographic Office. 2nd Stereotyped Edition... .. . ... ... 12 O Ni»W Log and Versine Altitude Tables (Reprinted from the 2nd Edition of above Book), by Lieut. Radler de Aquino (Brazilian Navy). The simplest and readiest way of finding the Altitude by means of logarit)i?ns ... ... ... ... ... 2 6 DOUBLE ALTITUDES. Method for finding the Latitude by the Simultaneous Altitudes Of Two Stars, by Capt. Burdaood, R.N. (reprinted 180C) 1 COOKERY. Ship's Cook and Steward's Guide, containing Hints for Management, and Two Hundred and Fifty Recipes, by Jawe* B. Wilton ... ... 1 List of Eautical Works published by J. D. POTTER. AZIMUTHS. Sun's True Bearing or Azimuth Tables, by John Burdwood, (Staff Commander, R.N., of the Hydrographic Department, Admiralty.) The Revised Edition of the above, with Extensions in Latitude, Declination and Hour- Angle, has been prepared, with the permission of H.M. Stationery Office, bv Percy L. H. Davis, FM.A.S., Chief Assistant (retired) in H.M. Nautical Almanac Office ... ... ... ... ... ... ... 8 6 This book contains a complete set of " Horizon Tables " for the reduction of observations. Davis's Sun's True Bearing, or Azimuth Tables (30° N. to 30° S.), by J. E. and Percy L. H. Davis. The only means of ensuring a correct course at sea is by the use of calculated or tabular azimuths, and the latter render the operation speedy and accurate. These tables, an addendum to those of Capt. Burdwood, R.N., which preceded them, have been in very general use since their publication. The instructions in several European languages have proved of great service to foreign seamen 11 6 (Supplied to H.M. Fleet by Admiralty order.) Davis's Supplementary Azimuth Tables (now published separately). The Time Azimuth Tables in general use do not often give azimuths near the meridian, which are in frequent demand for ex-meridian observations, but they will be found in this book, in addition to complete tables extending to latitude 64° 8 (Supplied to H.M. Fleet by Admiralty order Davis's Star Azimuth Tables, computed for all latitudes between 60° North and 60° South, by P. L. H. Davis. This book has followed on the very general adoption of stellar observations as a means of navigation, and supplies the seaman with the same details regarding stars, as he can get from "Burdwood and Davis" when the sun is concerned. Some ingenious altitude marks are used for the first time in these tables which materially aid in the identification of any hastily observed star, as to which doubt may exist 11 6 (Supplied to H.M. Fleet by Admiralty order.) High Latitude Tables, between 61° and 78°. By Percy L. H. Davis 7 This work, which was originally prepared for and used by the Antarctic Expedition of 1901, has now been adopted for use in H.M. Xavy and will certainly be a necessity in all ships trading to northern ports. (Supplied to H.M. Fleet by Admiralty order.) Short, Accurate, and Comprehensive Altitude-Azimuth Tables to show the true bearing of the Sun, Moon, Planets, &c, for latitude 0° to 75 c north or syuth; altitudes 0° to 75°; and declination 30° north to 30° south ; also the Approximate Ship Time, by A. C. Johnson, B.N. (Published by request) 3 6 (Supplied to H.M. Fleet by Admiralty order.) Captain Weir's Azimuth Diagram 1 6 (Supplied to H.M. Fleet by Admiralty order.) Time Azimuth Diagram, by Hugh Godfray, M.A 3 u 4 List of Nautical Works published by J. D. POTTER. CHARTS. s. d. Charts: their use and meaning, with thirteen figures and eight charts, by Dr. G. Herbert Fowler ... 4 o This, which is believed to be the first book on charts yet published, brings together information which hitherto h. ; s been obtainable only from verbal teaching. It deals with Mercator and Gnomonic navigational charts, and with Meteorological and other scientific charts, frcrn a practical point of view in simple language. CHRONOMETERS. Davis's "Chronometer" Tables; or, hour angles for selected altitudes between latitudes 0° and 50°, with variations for 1' in all elements, by P. L. H. Davis. Means of working a Sun "Chronometer " arithmetically have been for many years a desideratum, and have been published, in 1793, by Lalande ; in 1827, by Lynn ; and by Hommey, in 1863 ; but Mr. Davis, by the omission of useless or undesirable altitudes, and the inclusion of Variations in l'of Altitude, Latitude ami Declination, has made a table of great practical utility. The book, 'as a substitute for or a check on logarithmic calculation, is almost a necessity, and is especially useful in latitudes less than 45°. A comparison has been made in actual work of the tabular results with those obtained in the ordinary way, showing practically identical results ... ... 11 6 Notes on the Management of Chronometers and the Measurement of Meridian Distances, by Rear- Admiral Charles Shadxvell, F.R.8. (1861) 4 6 EQUAL ALTITUDES. Tables for Facilitating the Method of Equal Altitudes, by F. A. L. Kitchin, B.A., Naval Instructor, R.N. ... ... ... ... ... ... ... ... ... 1 COMPASS. Rev. William Hall's Visible Astronomical Compass, for Lat. 50. Channel and adjacent zone. Important for sea and air navigation, size, Gin. diameter ... 1 An Explanation of the Adjustment of Ships' Compasses, illustrated with numerous diagrams, by Captain the Honou vynd, R.N. ... 2 Handbook to Beall's Compass Deviascope, by Captain George Beall, contains, in addition to a complete explanation of this well-known instrument, much information necessary to compass correction ... ... ... ... ... 1 6 Elementary Manual for the Deviations of the Compass in Iron Ships, intended for the use of Seamen of the Royal Navy and Mercantile Marine, and Navigation Schools, by E. W. Creak, C.B., F.R.S., retired Captain, R.N. 10 Practical Information on the Deviation of the Compass, for the use of ^1 Masters and Mates of Iron Ships, by J. T. Towson, F.R.G.S | AND ' Supplement to the above ; being the Questions on the Deviation of the Compass f issued by the Board of Trade for the Examination for Masters' and Extra Masters' | Certificates, and Answers to the Questions, by Capt. William Mayes, R.N. J The Roxburgh Compass Error Card. For quickly and accurately correcting True and Compass Courses and Bearines by a New Method ; extremely simple and easy to work. Size 10 X 11 inches, printed in black and red; varnished. By C.B.Wylie 3 The Pocket Compass Corrector. Makes an error in applying variation and deviation almost impossible ... ... ... ... .. ... ... ... 2 The Binnacle Compass, Corrected by itself, or the Deviation found with one Compass by both methods, and the Corrections applied, by Capt. A. B. Becker, Ji.N. 1 The Storm Compass, or Seaman's Hurricane Companion, containing a familiar explanation of the Hurricane Theory, by Capt. A. B. Becker, R.N., illustrated with Diagrams and Accounts of Hurricanes ... ... ... ... ... ... ... 1 6 Plain Deviation Curve Diagram, by Captain J. C. Robinson u 6 5 List of Nautical Works published by J. D. POTTER. GREAT CIRCLE SAILING. a. d. A Chart Of South Latitudes, beyond 20 degrees, to facilitate the practice of Great Circle Sailing ; with an accompanying diagram for the determination of the courses and distances, by Hugh Oodfray, M. A. ... 3 EX-MERIDIANS. Davis's Ex-Meridian Tables and Supplementary Azimuths, by P. L. H. Davis. This important woi-k contains Calculated Keducticms to the Meridian for hour angles less than 7o m and altitudes lower than 84°, Declinations and Latitudes 3-±° and 64° N. and S. The use of the book is quite easy to anyone familiar with the Azimuth Tables. The Supplementary Azimuths, which accompany it, give bearings too near the meridian for inclusion in ,; Burdwood and Davis," which are now in great request for position lines and ex-meridian work ... ... ... 11 6 Tables for the Reduction of Ex-Meridian Altitudes, by J. T. Towson,F.R.G.S. 1 Ex-Meridian Diagram, by F. A. L. Kitchin, B.A., Naval Instructor, R.N 1 EOUR ANGLES. Tables of Calculated Hour-Angles and Altitude Azimuth Tables, 30°N.to30°S. Ex-'vSerid'an Tables and Calculated Reductions and Azimuths of Bright Stars, 60° N. to 60' S., by H. S. Bl.iclbume 7 6 The Calculated Reductions and A zimuths of 27 of the brightest stars up to about one hour from Meridian abov* the Pole, and from two (-o thre > i the Pole for eircumpolar stars, make accural* position finding- from two stars at fcwilig it si apler th*n by any pre . Lously published tables. The " Excelsior" Azimuth and Position Finding Tables (being the Second Edition of the above book, 1916) H. S. Blackbunw 10 6 HYDROGRAPHICAL ENGINEERING. An Essay on Hydrographical Engineering, as applicable to Floating Sea Barriers, Harbours, Batteries, Coast Defences, and Naval Fortifications, by Capt. Adderly Sleigh, K.T.S., F.R.S.L. (with Illustrations), (1859) 10 INTERPOLATION. Notes on Interpolation, Mathematical and Practical, by Rear-Admi ral C. Shadivell F.R.S 2 LATITUDE AND LONGITUDE. On Finding the Latitude and Longitude in Cloudy Weather and at Other Times, by A. G. Johnson, R.N. Enlarged to 56 pages, with Appendix and Part II % Short Tables and Rules for finding Latitude and Longitude, by Single and Double Altitudes, Pole Star, Lunars, &c, by A. C. Johnson, R.N. ... ... ... 3 Scales of Latitude from 5° to 60° proportional to a scale of Longi- tude, Where ^ in. = one mile, arranged to facilitate the finding of position from two Sumner lines, by R. E. Pealce, A.M.I.C.E. per set 5 Charts to accompany above each 2 6 Tables showing the Length in Feet of a Degree, Minute, ana Second of Latitude and Longitude, with the corresponding number of Statute Miles in each Degree of Latitude ; and the number of Minutes of Latitude or Nautical Miles contained in a Degree of Longitude, under each Parallel of Latitude, by R. C. Carrington, F.R.G.S. (1868) 1 LAW. Handbook on the Law and Practice relating to Apprentices to the Mercantile Marine Service, by F. W. Gardner (of the Middle Temple) ... 1 6 LIGHTS. Light Range Table (height of light, 10 to 1000 feet ; and height of eye, 10 to 12C feet), compiled and arranged by /. S. Commaiuder, Master Mariner ... ... ... 6 Lights in Lyrics, or a Glauce at the Channel Lights as Piloting Marks, on a run from Scilly to the Nore, accompanied by a Parting Precept on Compass Deviation, addressed to ail younger Mariners. With a view of the Casquets, Notes and Charts. (1859) 1 6 List of Nautical Works published by J. D. POTTER. LUNARS. «. d. Notes on the Reduction of Lunar Observations, Mathematical and Practical, by Rear-Admiral C. Shadwell, F.R 8. (1881) 4 6 See also Latitude and Longitude. LOGARITHMS. Davis's Requisite Tables (Logarithmic), by P. L. H. Davis. Tables of Logarithms to five places of decitn-tls only, for practical sea work. The typography and arrangement of the book will render it suitable for habitual use, and it coutams a table of Logarithmic and Natural Haversines specially designed for modern navigation ... ... ... ... ... ... ... ... ... ... ... 7 6 Davis's Five-Figure Logs and Anti-Logs, by P. L. H. Davis. Specially pre- pared for use in Actuarial and General Calculations. These tables are very iegible and do not fatigue the eye in use ... ... ... ... ... ... ... 5 Ditto ditto witb Index Tabs 6 MAST-HEAD ANGLES. Tables Of Mast-Head Angles, for five feet intervals, from 30 to 280 feet, and varying distances from a cable's length to four miles, with their application to Nautical Surveying; also the determination of distance by sound, with an example 2 MEASURES. Foreign Measures and their English Values, compiled from Official Sources, by R. C. Carrington, F.R.G.S. (1864) 7 6 MERCANTILE MARINE. A Voice from the Quarter-Deck on the State of our Mercantile Marine, by Joseph Mayne (Master Mariner) (1876) 1 An Address delivered to the Boys of the Training Ships " Chichester " and " Arethusa," by G. M. Coxhead (1885) 4 METEOROLOGY. Solectrics ; a theory explaining the causes of Tempests, Seismic and Volcanic Disturbances, and how to calculate their time and place. Illustrated by over 150 diagrams, by Alfred J. Cooper, Navigator. (Second Edition) ... ..." ... 6 The Causes of Weather and Earthquakes (with four Diagrams), bv Alfred J. Cooper (1902) ,.", 2 Light as a Motive Power, a Series of Meteorological Essays (1875), by Lieut R. H. Armit, R.N. ... _ 15 See also Winds. REVERSIBLE TRANSIT INSTRUMENT. Notes on the use of the Portable Reversible Transit, and the Method of Calculation of the Observations, with diagrams and photographs, by Capt. C. E. Monro, R.N. 3 q ROYAL NAVY. Chart of the Navy of Great Britain, from the Earliest Period of History, compiled from Historical publications, old records, Parliamentary returns, and other authorities, by Frederick Perigal (of the Admiralty), 1860 ' 3 6 RULES OP THE ROAD. The Rules of the Road at Sea, comprising the Regulations for preventing collisions at Sea, 1897, and Rules in force in Harbours, Rivers, and Inland Waters ; with explanatory notes and observations, by H. Stuart Moore, of the Inner Temple aiid the Admiralty Court, Barrister-at-Law. (Third Edition) 7 Q Diagrams, with Explanations, illustrating the Rule of the Road for Sailing Ships, by Capt. H. S. Blackburne 2 3.H (How's Her Head) Indicator and Rule of the Road at Sea, by George Spillane ... .16 7 List of Nautical Works published by J. D. POTTER. NAVIGATION AND NAUTICAL ASTRONOMY. s. d. The "Conway" Manual of Navigation. In this book of 80 pages nothing is taken for granted. All formulas are proved and the dependence of Navigation and Nautical Astronomy upon the solution of Plane and Spherical Triangles is clearly brought out. Particular emphasis has been laid upon method. By J. Morgan, M.A. (Senior Master) and T. P.Marchant, A. L. Wood (Navigation Masters), H.M.S. " Conway " School Ship 5 Nautical Astronomy, by W. P. Symonds (Ex.-Cummissioner of Surveys). The best methods of calculating Hour-Anarle, and finding Longitude and Latitude. The shortest Ex-Meridian method with New Table. Sidereal and Mean Time made clear. Tlie New Navigation explained and the Modern methods of working Double Altitudes, and drawing Position lines. The Equation of Equal Altitudes made easy, and used for finding Longitude from Ex-Meridians, and for determining error in Latitude due to Ship moving N. or S. Lunars simplified. Chapters on finding Distances, the Tides, &c, with many diagrams ... ... ... ... ... ... ... ... ... 6 Nautical Astronomy Made Easy, by A. C. Johnson, B.N. All the Rules being worked by a Small Table on One Page, designed to economise Time and Labour ... 3 An Introduction to the Practice of Navigation and Nautical Astronomy, by R. E. Hooppell, M.A., F.R.A.S. 3 6 The Practice of Navigation and Nautical Astronomy, comphte with tables, by Lieut. Raper, R.N. ... ... ... ... (See also the "New " Navigation) 18 Nautical Tables, by Lieut. Raper, R.N. ( do., do. ) 14 Inman's Nautical Tables. A New Edition of tin's standard work, revised and brought thoroughly up to the present date, by the Rev. William Hall, R.N., and containing all the aids to rapid fixing of position which are essential in modern Navigation ... ,., .,. ... ... ... ... ... ... ... ... 18 Lectures on Elementary Navigation, by Rev. J. B. Harbord, M.A. (Retired Naval Instructor, R.N. ; late Inspector of Naval Schools, Admiralty ; Examiner in Navigation and Nautical Astronomy for the Department of Science and Art ; Author of " Glossary of Navigation ") ... ... ... ... ... ... ... 7 6 Navigation Simplified, by a System of Teacliir g based on First Principles, for Officers (from 2nd Mate to Extra Master) in the Mercantile Marine and Yachtsmen. Illustrated by numerous diagramt, by Captain P. Thompson, F.R.A.S., Younger Brother of the Trinity House, Senior Examiner of Masters and Mates, and Secretary to the Local Marine Board of London ... .. ... ... ... ... ... 12 Examination Diagrams Simplified, for Navigation Students; illustrated by sixteen diagrams (including 5£ inch Boxwood Scale), bv Captain P. Thompson, F.R.A.S " 2 6 Navigation, intended for Self-Instruction up to the Second Mate's Examination, by William Roy ... . 6 Practical Coastal Navigation, with numerous charts and diagrams, by Count de Miremont ... ... ... ... ... ... ... ... ... ... ... 4 Tables of Allowance for Current when affecting Compass Course and Ship's Speed, by Capt. O. E. Hoar, War Department Fleet. A small aud convenient Table to give by inspection the correction to a Compass Course made necessary by a Current in any direction, and the resulting distance made good. A desirable book for all Coastwise Navigation 2 "THE 'NEW NAVIGATION." Appendix to Raoer's Practice of Navigation. Being an explanation of the New Astronomical Navigation by the method of Calculated Zenith Distances, with Soecial Tables for Simplifying and Shortening the work, by William Hall. R.N., F.R.A.S., Chaplain and Naval Instructor (Chief Naval Instructor, Royal Australian Navy) 1 See also Altitude Tables. List of Nautical Works published by J. D. POTTER. SAILING DIRECTIONS. d. Canadian North Atlantic Steamship Routes between the British Isles and Canada. Distance, Latitude, Longitude, Variation, and true Course, by R. A. Woodward, Lieut B.N.R 5 Correct Magnetic Courses and Distances, from and to Various Ports round the British Isles, by Arthur Underhill, LL.D., Commodore of the Royal Cruising Club, assisted by several Members of the Club. Second Edition ... ... 2 Concise Navigating Directions for the River Thames, including all the Pools, Readies, and Channels, from London Bridge to the South Foreland and Oifordness, and for the English Channel to Beachy Head; also for the Port of Dunkt-rque and the approaches to the Scheldt, by Stephen Penny, Trinity Pilot, Gravesend (illustrated by nineteen Charts) 7 6 East Coast Rivers. Charts and Sailing Directions for the Rivers Roach, Crouch, Blackwater, Cc lne, Stour, Orwell, Deben, Ore and Aide; together with General Charts Irom the Thames to Southwold, by Lieut. S. V. S. C. Messum, R.N 5 The Pilot's Guide for the English Channel (with which is now incorporated "The Pilot's Handbook for the English Channel" by Staff Commander J. W. Kintr, R.N.), comprising the South Coast of England, and general directinns for the Navigation of the Channel ; with numerous Charts and Plans of Harbours, edited by H. D. Jenkins, F.R.G.S 10 A Chart of the Dutch Waterways, by J. & A. B. Powell 4 o From Calcutta to Bombay Coasting, being the Second Edition of the Hand- book to the Ports on the Coast of India between Calcutta and Bombay, including Ceylon and the Maldive and Laceadive Islands, with 11 Charts and 12 Photographs, by Lieut. H. S. Brown, R.N.R., Port Officer, Marine Department, Madras Presidency. 1 The Occurrence and Paths of Storms, and the Method of Avoiding Damage from Them, by " Kail Siad." An Essay on "The occurrence and paths of those storms known as ' Cyclones,' as they are encountered in Eastern Seas between Aden and Singapore, including the neighbourhood of Mauritius and that part of the Indian Ocean between Mauritius and India. Also the method of avoiding damage I rum them" ... ... ... ... ... ... 1 Winds and Currents of the Mediterranean, by Capt. A. B.Becker, R.N., with remarks on its Navigation at different Seasons of the Year, compiled from various authorities, chiefly Spanish (1864) 3 o Navigation of the Atlantic Ocean, by Capt. A. B. Becher, R.N., with an account of the Winds, Weather and Currents found therein throughout the year (with Charts) (1892) - ... ...50 Navigation of the Indian Ocean, China and Australian Seas, by Capt. A. B. Becher, R.N., with an account of the Winds, Weather, and Currents found therein throughout the year (with Charts) (1864) 5 Chart Of the Sulina Branch Of the Danube (European Commission of the Danube), surveyed by Robert Hansford, Surveyor of the Commission, under the direction of C. A. Hartley, Engineer in Chief (showing 45 nautical miles of the River from Sulina), size 10 ft. x 2 ft 3 in. (1860) 20 Notes On Cherbourg (Geographical and Historical description of, Ac), and Chart (1858), by Commander Bedford Pirn, R.N., F.R.G.S 1 SALVAGE. How Ships are Lost, and How to Save Life and Property at Sea (Illustrated), by W. P. B. Manser (1877), 1 9 List of Nautical Works published by J. D. POTTER. SEAMANSHIP. s. d. Under Square Sail, by Capt. Withers (1898) 2 Under the Red Ensign; or, "Going to Sea," by Thomas Gray (1892) ... 1 6 SEXTANTS. Stars and Sextants. Star Distance Tables for facilitating the use of Lord Ellenborough's method of Correetinsr the Centring and Total Errors of Sextants at Sea, by John Abner Sprigge, Wm. Iraser Doak, M.A., F.B.A.S., T. Charlton Hudson, B.A., F.B.A.S., of H.M. Nautical Almanac Office, Admiralty, and Arthur S. Cox, B.Sc., A.R.C.S 2 6 Captains' and Officers' Bridge or Poop Companion. Tables for finding the distance of an object at sea by inspection (without the use of pencil or paper), afc the same time giving the distance the ship will go wide of the object before getting to it, and the course to steer to obtain a required distance. The anove gives, with the aid of a compass only, the distance of a moving ship from any fixed object. By A. Hiitteroth Course and Position by Sextant Observations of two known Objects, by Lt.-Col. English, late B.E 6 SHIPPING. Historical Notes on Shipping, by p. L. Isaac, M.I.N.A. (1879) l SPEEDS. Speed and Consumption of Steam-Ships and Stability, with Algebraic Formula for Economical Speed, and Rules for calculating the alterations in Draught and Trim corresponding to Changes in Displacement, and for using the Hydrometer to estimate those due to Differences in the Specific Gravity of the Water ; for use in the Royal Navy and Mercantile Marine ; to which has been added a Chapter on Stability, with Practical Rules; Second Edition, Revised and Enlarged, by J. F. Buthven, Master Mariner, late Lieut. B.N.B., Assoc. Inst. N. A., Younger Brother of tlie Trinity House, F.B.G.S -1 Speed Tables, for finding the distance run in a given time at a given speed, between the limits of 10 to 18 knots, by J. D. Macpherson (Pacific Steam Navigation Co.) ... 1 STABILITY. A New Theory of the Stability Of Ships, second edition, revised and enlarged (with 28 diagrams), by Alf. J. Cooper (1899) 2 See also Speed and Consumption of Steamships. STARS. Steering by the Stars, for Night Flying, Night Marching and Night Boat-Work, between Lat. 40° N. and 60° N., with Sketch Maps and Directions for finding the selected Stars. By James Dundas White, LL.D., M.F. ... ..10 Position-Line Star Tables. A new and simple method of fixing ship's position by observations of stars near Meridian and Prime Vertical without logarithmic calculation, by H. B. Goodwin, B.N. [These Tables have been adopted officially in the United States Navy.] 5 C The Bearings of the Principal Bright Stars of greater declination than 23 u north or 23° south ; also those of the Moon and Planets when similarly situated, by A. C. Johnson, B.N. (Published by request) 3 Pole-Star Latitude : a Method of Finding the Latitude from an Altitude of the Pole Star, by Damton Hutton (Master Mariner), B.A., M.Inst.C.E 1 Tables for Facilitating the Determination of the Latitude and Time at Sea by Observations of the Stars, by Rear-Admiral C. Bhadwell, F.B.S. 2 6 A Handbook for Star Double Altitudes, by A. C. Johnson, B.N., with directions for selecting the Stars ... ... ... ... ... ... ... ... ... 2 6 See also Sextants. List of Nautical Works published by J. D. POTTER. SIGNALS. s. d. Signal Cards— British System, with PlateB, containing Instructions for Sema- phoring by Day, and with the MorBe Code by Day or Night, together with the principal " Urgent " Light or Sound Signals, in accordance with the New Code. Also, Sheet of New Code Flags (34 Flags, coloured). Compiled by J. Whitly Dixon (Retired Captain, Royal Navy). (Size, 24^ x 19£) 1 6 Ditto ditto mounted on thick card 2 SUKVEYING. Practical Nautical Surveying and the Handicraft of Navigation, bv Com. T. A. Hull, R.N. 3 Practical Observations on Surveying (on determining the Position of a Vessel when Sounding), by Commander P. F. Shortland, R.N. 1 TIDES. "'How far is that Light?" Tables to allow for current in finding the distance by doubling the angle on the bow, by Fredk. Ball, M.A. ... ... ... ... 1 Capt. D. Fulton's Tidal Diagram, an easy and ready method of computing the correction to be applied to the soundings, mounted on stiff cardboard with Rule and Case complete ... ... ... ... ... ... ... ... ... ... ... 4 Moxly's Theory Of the Tides, with numerous diagrams, Second Edition, Revised and Enlarged, by Capt. J. F. Ruthven, F.R.G.S 5 Tide Charts of the English and Bristol Channels and entrance of the Thames, compiled from the Admiralty Tide Tables, by Algernon Heber Percy, late Lieut. Royal Navy ... ... ... ... ... ... ... ... ... 5 The Direction and Rate of the Tidal Streams at every Hour, for 48 Localities between the Nore and Scilly Isles, compiled from Admiralty Sources only, by F. Hoivard Collins ... ... ... ... ... ... ... ... 2 The General Direction of the Tidal Streams in the North Sea for every Hour " before " and " after," and at High Water, Dover, compiled by Com. G. K. Gandy, R.N.R., from Official Publications (on one sheet, size 23 by 17 inches) 1 The Universal Tidal Ready Reckoner, calculated by Capt. W. E.Hutchinson, l 6 The North Sea. Its Physical Characteristics, Tides, Currents and Fisheries, by W. H. Wheeler, M.Inst.C.E. 2 6 TIME. How to Find the Time at Sea in less than a Minute, being a New and Accurate Method, with specially adapted Tables, by A. C. Johnson, R.N. ... ... '.\ Time, Tide, and Distances. A handy book of reference for the Shipowner, Underwriter, or Traveller. Contains the World's Time compared with Greenwich ; the Tides round the British Coasts and those from Bergen via the Eastern Route to Japan with that at London Bridge ; approximate Distances from Home Ports to Home and Foreign Ports (over 13,000 references) ; and a Speed and Distance Table for Rates of Speed from 8 to 21 knots for distances up to 14,000 nautical miles, by J. McKirdy, R.N.R 15 Time-Altitudes for Expediting the Calculation of Apparent-Time, &C, by A. C. Johnson, R.N. ... ... ... ... ... ... ... ... ... 4 U Th© Blue Coat Boys' Clock. A dial showing the simultaneous time of day at all parts of the earth's surface, size 20 x 17 inches 5 List of Nautical Works published by J. D. POTTER. WINDS. b. d. The True Direction and Velocity of Wind, obsprved from Ships while Sailing, by James N. Miller (Member of the Liverpool Polytechnic Society), with Table for Indicating the True Direction of the Winds at Sea (1870) 6 The Wind in its Circuits: with the explanation of the Origin and Cause of Circular Storms and Equinoctial Gales ; illustrated with numerous Diagrams and a Chart of the Prevailing Winds of the World for Spring and Summer, by Lieut. R. H. Armit, R.N. (1870) 7 6 USEFUL PUBLICATIONS FOR YACHTSMEN. Amateur Sailing. Reminisoences by C. F. Abdy Williams 4 Navigation Simplified, by a System of Teaching based on First Principles, for Officers (from 2nd Mate to Extra Master) in the Mercantile Marine and Yachtsmen. Illustrated by numerous diagrams, by Captain P. Thompson, F.R.A.S 12 Practical Coastal Navigation, with charts and diagrams by Count de Miremont 4 Concise Navigating Directions for the River Thames, including all the Pools, Reaches, and Channels, from London Bridge to the South Foreland and Orfordness, and for the English Channel to Beachy Head; also for the Port of Dunkerque, and the approaches to the Scheldt, by Stephen Penny, Trinity Pilot, Oravesend (illustrated by nineteen charts) 7 6 East Coast Rivers. Charts and Sailing Directions for the Rivers Roach, Crouch, Blackwater, Colne, Stour, Orwell, Deben, Ore and Aide ; together with General Charts from the Thames to Southwold, by Lieut. 8. V. S. C. Messum, R.N. 5 The Pilot's Guide for the English Channel (with which is now incorporated "The Pilot's Handbook for the English Channel"), comprising the South Coast of England and general direction for the Navigation of the Channel ; with numerous Charts and Plans of Harbours, edited by H. D. Jenkins, F.R.O.8. ... ... ... 10 A Chart of the Dutch Waterways, by J dk A. B. Powell 4 o Correct Magnetic Courses and Distances, from and to Various Ports round the British Isles, by Arthur Underhill, LL.D., Commodore of the Royal Cruis-ng Club, assisted by several Members of the Club. 2nd edition ... 2 3 H (How's Her Head) Indicator and Rule of the Road at Sea, by George Spillane 1 6 The Roxburgh Compass Error Card. For quickly and accurately correcting True and Compass Courses and Bearings by a New Method; extremely simple and easy to work. Size 10x11 inches; varnished. By C. R. Wylie 3 ADMIRALTY CHARTS. Official Catalogue of Admiralty Charts, Plans, and Sailing Directions. A Vol. of 330 pages and 24 Index Charts Ko charge. On the Correction and Use of Charts, Light Lists, and Sailing Directions. 40 pp., bound red cloth ... , » Ko charge. 12 42 1 a m n£ 2 ** S ui 2* V for various yea' uring that perio O o L^ O «0 o O r< O u > «* s CO CM O co co *l a © of l-H CM OS CO_ o aT a? .-a z o» as CM 00 oo 00 >o CO oo +3 — 42 ?■» 8 6 1 o . O Z I » p co U3 St ■ ||. s * -«* T o CO CM Tfl CM O N Oi M XL 3 •1 I CM t^ 00 CO O^ T-* CM" fcCQ PUBLISHED FOR EVERY Catalogues (gratis) frc J. D. POT' 1 • •rO \r of Charts pr in the Vepartr 3 3 to a :_, P- 2 S Minor Corrections at the hands of the Draughtsmen. 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