The mariners magazine, or, Sturmy's mathematical and practical arts containing the description and use of the scale of scales, it being a mathematical ruler, that resolves most mathematical conclusions, and likewise the making and use of the crostaff, quadrant, and the quadrat, nocturnals, and other most useful instruments for all artists and navigators : the art of navigation, resolved geometrically, instrumentally, and by calculation, and by that late excellent invention of logarithms, in the three principal kinds of sailing : with new tables of the longitude and latitude of the most eminent places ... : together with a discourse of the practick part of navigation ..., a new way of surveying land ..., the art of gauging all sorts of vessels ..., the art of dialling by a gnomical scale ... : whereunto is annexed, an abridgment of the penalties and forfeitures, by acts of parliaments appointed, relating to the customs and navigation : also a compendium of fortification, both geometrically and instrumentally / by Capt. Samuel Sturmy.

CHAP. XVII. How to keep a Sea-Journal, that so every Sea-man, Navigator, and Mari∣ner, may not be ashamed to shew their Account to any Artist, and by it benefit themselves and others.

I Would not have any ingenious Sea-Artist, that hath a long time kept Account of a Ship's way, and hath been Commander or Mate many years, to think I pre∣scribe him Rules, and to perswade him out of his beaten Path (No, I think that a hard matter.) But we prescribe Rules for those that are but new Learners, that so they may have a perfect Method and Way of keeping Account of a Ships way at Sea; that if the Master should perceive an Ingenious Practicioner aboard, and by exami∣ning his Journal find him able, might at his return home give him encouragement, by speaking in his behalf to other Men to make him a Mate; and that is the way to encourage Artists: But I confess the greatest Dunces have commonly the best Imploy∣ments, and many abler men before the Mast: which is great pity, that the deserving Men had not their right. But what shall I say? There is such an aversment in Fate. Therefore I shall proceed to our Journal. I conceive it will be fit to have a Book in Folio, that a sheet of Paper makes but two Leafs, and to keep the left side of your Book void, that you may write all the Passages of the Voyage; that is to say, when you set Sail, with what Wind, and what Ships are in company with you, and how far you keep company; what Storms, and how the Wind was: and likewise put down the time that you come by any misfortune, of cracking or breaking a Mast or Yard, or if any Men should die; and also what Damage you receive by any Storm, and the like Occurrences, as you shall think requisite; and what Currents and Variation you meet with. But before all this, put down the Title of the Voyage, over the left-hand Page, in these or such like Words, viz.

A JOURNAL of our Intended VOYAGE by God's Assistance from Kingrode-Port Bristol in Latitude 51 deg. 30 min. to the Island of Madara in Latitude 32 deg. 10 min. and from thence to Barbadoes in Latitude 13 deg. 10 min.

The right side of your Book throughout may be divided into 13 Columns, by Lines, as you may see in the following Example.

In the first must be expressed the day of the Month, in the second the Letter of the Week-day that Year; put it once in the top of the Page: In the third Column the Months; make him large enough to put down the Latitudes you make by Observa∣tion of the Sun or Stars, and Currents, and how they set: In the fourth, the Course steered by the Compass: In the fifth, the Variation of the Compass, if there be any; or else the Variation by Currents, if there be any. Set down the Angle of the Rhomb, it made with the Meridian in the sixth Column; and in the seventh, the Distance sailed in Leagues or Miles: In the eighth, ninth, tenth, and eleventh Columns, set down the Northing, Southing, Easting, and Westing: In the twelfth, the Latitude by Dead Reckoning; and in the thirteenth Column, the Difference of Longitude from the first Meridian, according to Mercator's Chart, or the Arch of a Great Circle, or a Polar Chart or Globe.

1666.	Month Days.	Week Days.	A Journal of our Intended Voyage, by God's Assistance, in the Good Ship the Eliz. of B. S. S. Commander, from Kingrode in Latitude 51 d. 30 m. to Madara in Latitude 32 d. 30 m. and from thence to Barbadoes, in Latitude 13 d. 10 m.
March	25	a	Set sail out of Kingroad, in Company with the John bound to Cales, and Ann•• bound to Virginia; the Wind at E. N. E. thick rainy Weather.

The Journal of our Intended Voyage, by God's Assistance, in the C. (of B.) S. S. Comman∣der, from Lundy, in Latitude 51 d. 20 m. to the Island of Madara, in Latitude 32 d. 30 m. Angle of Position, or Course S. S. W. 1 d. W. Distance 411 Leagues, Meridian Distance 167 Leagues, Difference of Longitude 11 d. 16 m. from Madara to Barbadoes, in Latitude 13 d. 10 m. Angle of Position or Course S. W. 61 d. 14 m. Distance 798 Leagues, Meridian Distance 698 Leagues, Difference of Longitude 41 d. 40 m.
		51 deg. 20 min.	Course	5 East	Degr. from the Merid. SW 25d. SW 61 d. 14 m.	Distan.	Diff. La	Diff. La.	M. dep.	M. dep.	51 d. 20′	diff. Lo.
		32 deg. 30 min.	SSW	Variation.	411	377	377	167	167	32 d. 30′	11d. 16′
		13 deg 10 min.	SWbW half W		798	387 lea.	387 lea.	698	698	13 d. 10′	41 d. 40
		Latitude by Ob∣servation.	Course by Compass.	Variation of Compass.	Degrees from the Meridian.	Dist. sailed.	North.	South.	East.	West.	Lat. By dead R.	Diff. of Longit.
		Degr. Min.	Points.	Degrees.	Degrees.	Leag. 10	Lea. 100	Lea. 100	Lea. 100	Lea. 100	D. M.	D. M.
26	a	Set sa••l March 25.	S b W half W	5 deg 30 min. E	SW 22 d. 30 m.	48		44 35		18 37	49 07
27	b		S b W half W	5 deg. 30 min. E	SW 22 d. 30 m.	49		45 27		18 75	46 51
28	c	44 deg. 31 min.	S b W half W	5 deg. 30 min. E	SW 22 d. 30 m.	51		47 12		19 52	44 30
28			Add up the Numbers, the sum is 148		136 74		56 64		04 14
29	d		SSW	2 deg. 45 min. E	SW 25 d. 15 m.	43		38 87		18 38	42 34
30	e	40 deg. 27 min.	SSW	1 degree East	SW 22 d. 30 m	46		42 50		17 60	40 26
31	f	38 deg. 30 min.	SSW	0 degr. East	SW 22 d. 30 m.	39		36 03		14 92	38 38
			Add up the Numbers, the sum is 128		117 40		50 90
			Correction by Observation 2 9		2 70		01 10	8
			The sum corrected is 130 9		120 10		52 00	38 30	07 43
			Difference of Latitude, Depart. from first Merid. 278		256 84		108 64
1	G	April, a Current sets E b S.	SW b S	11 d. 30 m. Cur.	SW 22 d. 30 m.	43		43 42		17 99	36 17
2	a	SW b S	11 d. 30 m. Cur.	SW 22 d. 30 m.	45		41 57		17 22	34 12
3	d	32 deg. 30 min.	SW b S	11 d. 30 m. Cur.	SW 22 d. 30 m.	42		38 80		16 07	32 19
		Set to th'Eastward by the Current in 3 days 22 Leagues and almost a half E b S by estimat.	Add up the Numbers, the sum is 134		123 79		51 28
		Correction by Observation 3 9	3 66		1 50		11
		The sum corrected is 131		120 13		49 78	32 30	10 46
4	c	Madara Island bears West distant. 8.58				8 58
		Difference of Latitude, Depart. from first Merid. 418		376 97		167 00	32 30	11 16
24	v	Set sail April 23. from Madara.	SW b S	5 d. 30 m. East by Current.	SW 28 d. 30 m.	36		31 75		16 97	30 55
25	c		SW b S	2 d. 45 m. East	SW 30 d. 45 m	46		39 46		23 65	28 57
26	d	27 deg. 43 min.	SW b S		SW 33 d. 45 m.	30		24 94		16 67	27 42
27	e	25 deg. 54 min.	SW		SW 45 degr.	51		36 06		36 06	25 55
28	f	23 deg. 47 min.	SW		SW 45 degr.	60		42 43		42 43	23 48
29	G	22 deg. 40 min.	SW		SW 45 degr.	28		19 80		19 80	22 47
			Numbers added, the sum is 151		194 44		155 58
			Correction by Observation 3		2 30		1 90	7
			Sum corrected is 154		196 74		157 48	22 40
29			Difference of Latitude, Depart. from first Merid. 572		573 71		324 48		20 47
30	a		SW b W	00 degr.	SW 56 d. 15 m.	45		25 00		37 42	21 25
1	b	May	SW b W	00 degr.	SW 56 d. 15 m.	47		26 11		39 08	20 07
2	c	18 deg. 57 min.	SW b W	00 degr.	SW 56 d. 15 m.	43		23 89		35 75	18 56
3	d		SW b W	00 degr.	SW 56 d. 15 m.	44		24 44		36 58	17 43
4	e	16 deg. 50 min.	SW b W	00 degr.	SW 56 d. 15 m.	39		21 67		32 43	16 37
			Add up the Numbers, the sum is 218		121 11		181 26
			Correction by Observation 7 8	4 33		6 50		13
			Sum corrected is 210 2		116 78		174 76	16 50
4			Difference of Latitude, Depart. from first Merid. 782 2		690 49		499 24		31 06
5	e	16 deg. 14 min.	WSW half W	5 degr. West	SW 67 d. 30 m.	31		11 86		26 64	16 15
6	G	14 deg. 03 min.	WSW half W	5 d. 30 m. West	SW 67 d. 30 m.	46		17 60		42 50	15 22
7	a		WSW half W	5 d. 30 m. West	SW 67 d. 30 m.	33		12 63		30 49	14 44
8	b	14 deg. 03 min.	WSW half W	5 d. 30 m. West	SW 67 d. 30 m.	30		11 48		27 72	14 09
			Add up the Numbers, the sum is 140		53 57		127 35
			Correction by Observation 5 2		2 00		4 80	6
			Sum corrected is 145 2		55 57		132 15	14 03
8			Difference of Latitude, Depart. from first Merid. 927 4		746 6		631 39		38 50
9	c	13 deg. 48 min.	W b S half W	5 degr. half	SW 84 d. 20 m.	55		5 39		54 73	13 47
10	d		W b S half W	2 degr. 50 min.	SW 87 d. 11 m.	60		2 94		59 92	13 39
11	e	13 deg. 10 min.	W b S half W	00 deg. 00 min.	SW 78 d. 30 m:	51		9 95		50 02	13 09
		Ship is in Lat. Bar∣badoes 69 lea. Ea.	Add up the Numbers, the sum is 166		18 28		164 67
11		Difference of Latitude, Depart. from first Merid. 1092		764 34		796 06		48 41
12	e	13 deg. 00 min.	West	5 d. 30′ Cur. sets	SW 84 d. 22 m.	39		3 80		38 60	12 59
13		The Current set S.	W b N	S. 2 d. 45′ Cur.	SW 81 d. 30 m.	26	81			25 71	13 10
13	G	13 deg. 11 min.	Difference of Latitude, Depart. from Lundy 1163		764 33		860 37	13 10	52 39
13		Barbadoes Island bears West distant of Leag. 5

Place this between folio 202. and folio 203.

Let this be our Example.

We will frame a Reckoning between the three Places before-mentioned, from Lun∣dy to Madara, from thence to Barbadoes, whose Distance in their Rhombs, and Diffe∣rence of Latitude, and Meridian-distance, I have put over in the head of the left-hand page, as you may see, answers to the words under. And in truth, I have found these Distances very near the truth; In two Voyages I differ but two Leagues, and that I was short. I worked it first out of a Mercator-Chart, and in Plain Sailing took the Product of that Work for my Distance, and Meridian-distance, and Course, as you have been already shewn in the first Question in Mercator-Sailing.

You see by the left-hand Page that we set sail the 25th day; but we entred it not in the right-hand Page until the 26th day at Noon: for it is to be understood,* 1.1 That since her setting sail March 25. to Noon of the 26th day, the Ship steers away and makes her Way good on the S. b. W. ½ W. Point of the Compass; but the Varia∣tion being 5 deg. ½ or half a Point to the Eastward, as you see in the fifth Column, therefore the Point she hath made good upon is only S. W. 22 deg. 30 min. as is ex∣pressed in the sixth Column: Upon this Rhomb she sails 48 Leagues, as in the seventh Column appears: And answerable thereunto I find in the Traverse-Table before-going, the Southing to be 44 35/1••0 Leagues, or by the Traverse-Scale 44 4/10. Leagues; and the Westing 18 37/100 Leagues by the Traverse-Scale 18 4/10 Leagues, as here in the ninth and eleventh Column appears by the Figures plainly set down. The Figures to the left hand signifie Leagues in this Journal, or Miles; and the two Figures to the right hand sig∣nifie the 100 part of a League: The Southing being 44 35/100 Leagues, which is 2 deg. 13 min. nearest; if that be substracted from the Latitude from whence you came, Lundy 51 deg. 20 min. it makes the Latitude the Ship is in at Noon to be 49 deg. 07 min. as appears in the twelfth Column. In the same manner, the second entrance, being the 27th of March, sheweth, that from the 26th day at Noon, to the 27th day at Noon, she made her way good upon the S. b. W. ½ W. Point of the Compass; but the Variation being 5 deg ½ Easterly, therefore the Angle of the Rhomb which the true Meridian was from the South to the Westward S. W. 22 deg. 30 min. and sailing 49 Leagues, the Southing is 45 27/100 Leagues, and the Westing 18 75/100 Leagues: So the La∣titude is now 46 deg. 51 min. So the third Entrance is the 28th day, the Course and Variation the same as before, and the Distance 51 Leagues; the Southing 47 12/100 Leagues, the Westing 19 52/100 Leagues: So the Latitude now is 44 deg. 30 min. You must understand the like manner of working of all the rest. What hath been said of a Reckoning may suffice; but it is of very good use to set down the Longitude in the last Column, and a Rule how to convert the Easting and Westing, that is, the Leagues or Miles in the East and West Column, into Degrees and Minutes of Longitude. I will give you this General Rule, that you may do it neer enough, without any sensible Error, on your Mercator Chart, or Polar Chart or Globe, provided these Rhombs differ not much one from another; by which Rule I found the Longitude for every Sum in the Journal. Say then,

As the Difference of Latitude,

To the Departure from the Meridian:

So is the Difference of Latitude in Meridional parts,

To the Difference of Longitude in Leagues or Miles.

The Difference of Latitude in the South Column summ'd up (as you must do as often as you have any notable Difference betwixt your observed Latitude and Dead Latitude) is 136 74/100 Leagues; omit the last Figure to the right hand 4/100, and then it will be 136 7/10.

The Departure from the Meridian in the West Column is 56. 64; omit the last Figure, it is 566: So you put them down.* 1.2

The Meridional parts for the Latitude 51 deg. 22 min. is	12002
The Meridional parts for the Latitude 44 deg. 30 min. is	9959
The Difference of Latitude in Meridional parts is	2043

Say then,

* 1.3As the Sum of the South Column, or Difference of Latitude 1367	313576
Is to the Sum of the West, or Departure from the Meridian 566	275281
So is the Difference of Latitude in Meridional parts 2043	331026
	606307
To the Difference of Longitude in Leagues 84 6/10	292731

Which reduced into Degrees is 4 deg. 14 min. for the 28th of March. So still you must remember to take the Sum of Difference of Latitude and Departure from the first Meridian. There are several other Rules you may see laid down before, for a Paral∣lel-Course of East and West, and other Rules to find the Longitude; as occasion re∣quires, you may make use of them: But this Rule saves you trouble, and comes neer enough in sailing several Courses.

* 1.4But let us proceed with our Journal. I observed the Meridian Altitude of the Sun the third day at Noon, that is from 30 at Noon to 31. I find my Latitude by obser∣vation 38 deg. 30 min. which, by Dead Reckoning it, is but 38 deg. 38 min. so the Dif∣ference is 8 min. Southerly; but being assured of a good Observation, I correct the Dead Reckoning thereby, by this Rule of Proportion, saying,

As the Sum of the North Column corrected is 1201	307954
To the Sum of the East Column corrected 520	271600
So is the aforesaid Increasing Southerly 27	143136
	414736
To the Increasing Westerly 1 17/100 Leagues	106782

* 1.5

Which is 1 League 1/10, and something more, not to be taken notice of. This Rule of Proportion Mr. Norwood hath laid down in page 111. of his Seaman's Practice, in the Description of his Journal in Miles, from Barmoodoes or Summer Islands to the Li∣zard; which method I do in many things follow, but not all: But this Rule that I propose is by the Traverse-Scale, which I hold best, which is thus.

By the Traverse-Scale.

Extend the Compasses from the Point made good in the last summing up, to the number of Leagues or Miles Difference of Latitude by Observation, and by Dead Rec∣koning, in the Line of Numbers; the same Distance will reach from some Points from the East and West, to the Difference of East or West.

As for Example.

Extend the Compasses from 2 Points and a little more (which was the Sum of the Course made good the 31 of March) unto 2 7/10 Leagues, which is 8 min. or there∣abouts in the Line of Numbers; the same Extent will reach from 6 Points to 1 1/10 Leagues and something more in the Line of Numbers, and that is the increasing Westerly. You may also with the same Extent correct the Distance, if you put one Foot at W or 100 in the Line of Numbers, the other will reach to the Distance 2 9/10 Leagues corre∣cted by Observation, as you see I have done in the Journal. So you see, That understand∣ing perfectly the Use of the Traverse-Scale, you may do the same, and more readily, as Mr. Norwood doth with his Table, to every Degree and Minute of the Quadrant, without sensible Error.

Now this Difference being found, I add therefore and put down in the South Co∣lumn the Difference 2 70/100 Leagues, and the West Column 1 16/100 Leagues, and under Distance 2 9/10 Leagues: Now the same corrected is by observation 130 9/10 Leagues, Distance 120 10/100 Leag. Southing and Westing 52 Leag. 8 min. substracted from the Dead Latitude, make 38 deg. 30 min. the true corrected Latitude according to observa∣tion:

Then I sum up the first Sums of the 28 of March, and this Sum corrected 31 of March together, and you have the Distance 278 Leagues,* 1.6 Difference of Latitude 256 84/100 Leagues, and Departure 108 64/100 Leagues, and by the Rules before-given 256 8/10 Leagues Southing, and 108 6/10 Leagues Westing; and with the Difference in Me∣ridional Leagues 364 7/10 Leag. I find the Difference of Longitude in Leagues 154 ••/10 Leagues, converted into deg. and min. is 7 deg. 43 min.

In like manner, upon the third of April I should be in Latitude 32 deg. 19 min. but by very good observation, I find the Ship in the Latitude 32 deg. 30 min. that is, not so much Southerly by 11 minutes: therefore to correct it by Observation, I put under Distance 3 9/10 Leagues, and in the South Column 3 66/100 Leagues, and in the East 1 50/100 Leagues, and under Dead Latitude 11 min. I substract the corrected Difference of Distance out of the Sum over it, and likewise the corrected Difference in the North Column out of the Sum in the South, and likewise the East out of the West Column, and add the 11 min. to the Dead Latitude, and then you have the Sum corrected; but if there be any Current, you may set it down, and allow for it, and note it down, as is that Example following the first of April to the third, and by your Traverse-Scale presently find how much the Current hath set you to the Eastward.

But if your Course be neer the East and West,* 1.7 it is sufficient to correct it in Lati∣tude only, as in the Example of the 12th and 13th of May; for in that Case the Longitude cannot be corrected but from some further ground. Now to set down this Reckoning upon the Plain Chart, or common Sea-Chart, it is needless and unnecessary: The better way is to set down every one of the Sums as they are corrected by Observa∣tion, in the same manner as you are directed in the latter end of the third Chapter of this Book; and so by the total Sums of the Difference of Latitude and Departure from the first Meridian, or Latitude and Meridian-distance, you may set it down on your Draught or Chart as often as you please with ease.

Now to set off every Sum corrected in Degrees of Latitude and Leagues of Longi∣tude, you have a Scale of Leagues or Miles for that very purpose, and Directions how to do it, in the ninth Chapter of this Book: But if you are desirous to set down your Reckoning in a Mercator or Mr. Wright's Chart, on in the Polar Chart, you have in the 12th and 13th, or last two Columns of your Journal, the substance and principal scope of your Reckoning set down as often as you sum up or correct your Reckoning: name∣ly, your Latitude and Longitude; which whensoever you have a desire to set down in the foresaid Chart, or any other graduated Chart, with Degrees of Longitude and La∣titude, you may readily do it.

As for Example. Suppose I would set down the Plat of the aforesaid Journal from the 25th of March to the 13th of May, I find the Latitude against the 25th of March 51 deg. 20 min. and the Latitude of the Barbadoes 13 deg. 10 min. and the Difference of Longitude 52 deg. 35 min. Therefore in the Latitude of 13 deg. 10 min. I draw or point out an occult Parallel, and reckon 52 deg. 35 min. from the Island Lundy towards the West: I draw by that Longitude an occult Meridian;* 1.8 the Intersection of this Meridian with the foresaid Parallel is the Point representing Bar∣badoes, or the Place of the Ship; and the like is to be understood of any of the other: And so I put down in the General Chart of Mercator the 8 Points of the Ship's Place, 1 a, 2 b, 3 c, 4 d, 5 e, 6 f, 7 g, 8 h, as there you may see. This form of keep∣ing a Reckoning is the most fit and agreeable of all others as I have seen or heard of, to all sorts of Charts, Maps, or the Globe it self, and to all kinds and ways of Sailing whatsoever.

Notes

• * 1.1

  Not that I do affirm the Vari∣ation to be Ea∣sterly for I know it to be 1 d. 30 m. West; but being neer the truth or not, it serves to exemplifie the Rule, that being the end for which this Ex∣ample is made.
• * 1.2

  But if you sail all on one Course, the Rule is in the third Probl, of Mercator Sailing.
• * 1.3

  As Radius 90 deg. To Tang. Rhomb: So difference of Lat. in Merid. parts, To diffe∣rence of Longi∣tude in Leagues or Miles.
• * 1.4

  8 min. is

  2 7/10 Lea. neer

  1201 to 520

  so 27:) 27

  3640

  1040

  14040
• * 1.5

  〈 math 〉〈 math 〉
• * 1.6

  This is because I find my self to the Northward, that is, less to the Southward by 11 m. than by Dead Reckon∣ing, & therefore less to the West∣ward 1 50/100 Leag. or so much to the Eastward, by reason my Course is in the S. W. Quarter, it must be corre∣cted in the con∣trary Quarter.
• * 1.7

  In sailing East and West, you have a Rule in Probl. 7. of sail∣ing by Mercator or Mr. Wright's Chart.
• * 1.8

  I hope this way will find good acceptation with the ingenious Mariner or Artist.