When a second edition of the map was published ca.1757, Mitchell added two large text blocks to the seventh sheet. These discuss the sources he used, in particular the latitudes and the very few longitudes he used to tie the geographical details to the map's framework of meridians and parallels. These two text blocks are transcribed here for the first time, the upper block first, then the lower block.

After the first Drawing of this Map in 1750, it was again corrected and improved before it was published, and I have since taken Care to procure & examine all the Information I could get, in order to render it as correct & usefull as possible; which has given occasion to this Second Edition of it; in which I have likewise inserted all the Observations I beleive we have for the Geography of N. America, since I find them grossly misrepresented by others.

The Foundation of this Map is the several manuscript Maps, Charts, & Surveys that have been lately made of our Colonies, which represent most Places from the Ocean to the Missisipi. But in order to know the true Situation of those Places, we must have their Latitudes & Longitudes, which are of much more Consequence in a general Map, than their bare Shape or Figure, which we only find represented in our Draughts & Surveys. But after having consulted all the Observations I beleive that we have, I found the true Situation, or Latitude & Longitude, of many Places was undetermined or uncertain; & that in the principal Parts on the Coast, and that we had no Accounts of them, but what might be found in the Journals of our Ships of War kept in the Admiralty Office; which I had recourse to for that reason, and have extracted from them whatever relates to our purpose, which are the chief Source of the Corrections & observations here inserted.

Since the Publication of this Map likewise I have examined & compared with other Accounts, the Observations of Mr. Chabert; which were not made when our Map was first drawn, nor known in England till after it was published; so that we neither followed nor rejected them.

From these authorities we find but two Alterations necessary in our Map: 1. In the Latitude of Cape Race: 2. In the Longitude of Cape Sable.

Column U2

In the Longitude of Caoe Race, different Reckonings in or Ships from Cape Breton, Canso, & Boston, differ 2 Degrees (on Accunt of the Currents), and more than Reckonings from Europe. At a Medium they make it in Longt. 53°.57'. Durrell's Survey makes it in 64°.9' & Chabert's in 53°.2' by its Distance from C. Raye: the Mean between them is 53°.35'.30": which is exactly the Mean o the Reckonings of our Ships of War from England.

C. St. Mary's they make 1°.20' West of C. Race; and St. John's Harbour 35' or 40' East of it.

Capt. Durrell in his Survey of this Coast makes C. Sable a Degree farther West from Canso, from which it was before laid down: and Chabert observes, that the French manuscript Charts & others, do the same. Our new Maps, blindly copyed from Chabert's, that make C. Sable in Longt. 65°.25' (according to Chabert's Reckonings, instead of his Observations), and Boston in 71°, make their Diff. Longt. 23' greater, we see, than our Ships make it.

The Map of New England & Nova Scotia requires a farther Consideration, as we find them very erroneously laid down in all our Maps & Charts, especially our many New Maps, copyed from a New Map of Nova Scotia, copyed from Popple and d'Anville: and those Errors are maintained by Arguments & pretended authorities, which seem to have confirmed them.

The only Authority they have for all this is a feigned Survey by a pretended Surveyor General Blackmore in 1711-12: who appears by his Journals to have been Lieutenant of the Dragon Man of War 1711, and made a rude Draught of this Coast (as

Column U3

well as he remembered it perhaps) in 1715, with a Petition to the Board of Trade to enable him to Survey it at that time, which he never did as we can learn. But this draught falling into the Hands of some Workmen, Mr. Moll published it as an Actual Survey "made by her Majesties especial Command," from which this Coast has been thus erroneously laid down ever since.

It is thus laid down from the Supposition that Mt. Desart Rock lies from C. Anne N.N.E. 30 Leags. and W. by S. 3 Leagues from Annapolis: from whence they make Mt. Desart I. in Lat. 44°.45' and the Rock in 44°.25'. But Surely it is well known that the Coast of New England runs rather E.N.E. than N.N.E., and that Mt. Desart is much farther from C. Anne than from Annapolis. Our Ships of War make Mt. Desart I. about N.E. 6 E. 50 Leags. from C. Anne. These observations then appear to have been made, as well as published, by Mr. Moll. There are no such Observations in Mr. Blackmore's original Chart in the Plantation office. Mr. Blackmore observed in the Dragon Holt I. in Lat. 44°.1', the Leostaff in Company makes it the same, and the S.W. End of Gr. Manan in 44°.39'; Govr. Dudley makes Pemmaquid Ft. in Lat. 43°.55'; Mr. Richer observed Pentagouet Ft. in 44°.22'; and Bellin laies down Mt. Desart Rock from observation in 44°.5'; all which observations agree with one another, and with the Journals & Reckonings of our Ships of War; whence Mt. Desart I. can never be in Lat. 44°.45'; nor the rest of that Coast so far North as this makes it.

By this they make the whole Coast of New England from 10 to 25 Min. of Latitude too far North, which leads Ships upon that dangerous Coast of Mt. Desart. Thence to Long I. they make the Course E.S.E. nigh 30 Leags. which appears to be about due East 20 Leags. Long I. & Gr. Manan, the two big Land-marks by which Ships steer, they make 50 & 60 Miles asunder instead of 29 or 30. By placing Quebec at the same time in Longt. 70°.35', they make the whole Country nigh a degree of Longitude & half a degree of Latitude out of its trrue Situation, which strangely misrepresents the whole.

In short, we do not find a single spot, hardly, justly laid down in these our New Maps of Nova Scotia, altho they were rightly laid down formerly by de L'Isle & others. We are so far from improving then in the Geography of America that we see it made worse & worse for want of certain Observations, which we have endeavoured to collect & thus to represent in one view.

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Lower text block of seven columns
Column L1

Observations of longitude most wanted are, C. Race, Charles-Town, and Niagara.

Wanted the Latitudes of Ft. Abitibis, Montreal, Ft. Frontenac, Niagara, Detroit, Cherakees, Creeks, Ft. Moore, &c. Different accounts make Montreal in Lat. 45°.20'.30' and 46°. Niagara in 43°; and 44°; Oswego in 43°.50'.22'.17' and 2', and that from pretended observations. In these uncertainties we observe a Medium between such different Accounts.

Wanted the Lat. C. Bonavista, Penguin I., C. Grat & Pt. Rich. Bellin makes C. Grat in Lat. 51°.30' by Obs. but he errs 16 or 20 min. in Lat. C. Race from the like Observations.

 

Cape Breton Isle	+	St. Pauls I. Nth. End ____________ by Chaberts Acct.		47.20 47.14
		North Cape or C. St. Laurence		47. 4
		Labrador Entrance		46.31
	*	Spanish River Entr.		46.24
		Gantent or Bird I. (Bellin)		48.00
Nova Scotia		Cape Rosiers by Accts.		49. 2
		Cape Ferone or Gaspee		48.57
		Canso Harbr.	)	45.25
		Frankland Harbr.	) Durells	45. 5
		Chebruchts Harbr.	) Accts.	44.31
		Chebruchts Head (Chabert)		44.32
		C. Sambro by Acct.		44.30
		C. La Heve		44.19
		Port Senior Isle		44.14
		Ragged Isles		44.52
		Port Wager		43.50
		C. Sable		43.25
		Seal Isl. Northern		43.31
		Long Isl. ________ by Chabert's Acct.		44.20 44.16
	* *	Annapolis Entrance __________________ Chabert		44.51 & 55 44.51
		St. John's Riv: Mouth		45.19
		Grand Menan I. Wt. End by Accts.		44.38
	+	Sable Isl. Wt. End ________ Chabert's Acct. ________ Et. End		44. 5 44. 6 44.12
New England	+	Mt. Desart I. by Acct.		44.20 & 30
		Holt Isl. in Penobscot B.		44. 1
		Piscataway Harbr.		43. 9
		Starr I. nigh Piscataway		43. 6
		C. Arane or Pigeon Hill		42.47
		C. Coded by Observation ________ by Accts.		42.00 42.10
		Boston Lighthouse by Acct. _________________ by Lat. Boston		42.30 & 35 42.20½
	+	New Haven Robies Acct.		41.20
New York		Monetock Pt. Et. End Long Isl.		41. 4
	+	Block I. Sth Side by Acct.		41.25
		Sandy Hook Pt.		40.25
		Never Sink Hills		40.20
Pensylvania		Cape Hinlopen		38.48
		Horeckill Road		38.54
	+	Bumstohook I. Nth End		39.30
Virginia		C. Charles		37.19
	*	C. Henry		37.00
Carolina and Georgia		C. Hatteras, Obs. __________ by Accts.		35. 9 35.10
	+ +	C. Fear, Obs. _______ by Accts.		33.59 33.50 & 55
	+	C. Romain		32.55 & 53
		Sullivans Isl. Sth Side		32.47
		Charles Town Barr		32.45
	+ +	Port Royal Barr, Obs. _____________ by Accts.		32.20 32.12
		Hilton Head	) Capt. Gascoignes	32. 9
		Tybec I. Nth End	) Accts	31.54
		St. Simmon's or Frederica Barr		31.12
		Jekyll Sound		31. 5
	+	St. John's Riv. by Accts.		31.18
		St. Augustine		29.45
Column L3		Mosquitos Inlet Southernmost		29.10 & 20
	*	Matanzas Inlet		29.29
	*	St. Davids Hd. Bermudas I.		32.25

Different Observations, which are too many to be all set down here, differ 4 or 5 Min. in which we take the difference between them.

All the Northern parts of America are made too far North, not only in our Maps & Charts, but in the Journals of our Ships, and all our Books of Navigation, Occasioned, I perceive, by their making no allowance for the [V]ariation of the Compass in Reckonings and Observations at a distance. Others make the Variation too great. Hence we have set down the Variation, where we met with good Observations of it; which they make 4 or 5 deg: greater in some Years.

In the many different Reckonings that Occur we take only those in Short Runs & fair Winds, taking the difference between these for the true Longitude. In these Reckonings I find no Accounts of the Variation; but I imagine some allow it, and some do not, as it is but small: if not allowed, the coast will be about 10' or 12' Longt. more East.

3. Capt. Fane in the Leostoff 1705-6, by several Runs backwards and forwards concludes the distance of C. Henry & Neversink to be 75 leagues, which with the Lats. 37° & 40°.20' makes diff. Longt. 2°.ll'. He makes it 1°.50' by taking Neversink to be in Lat. 40°.30', or allowing 5° Variation upon the Course made by this distance and diff. Lat.

Hence Cape Henry is at least in Longt. 76° or 76°.12', which our Mariners make 74° or 74°.30'.

Column L4

 

		Mean Long.
3. From Neversink to Charles Town without Allowance for Currents	( 7.45 ) ( 7.28 )	7.36
4. Do. from Cape Hinlopen		4.40
5. Do. from Cape Henry	( 3.48 ) ( 4.40 ) ( 4.00 ) ( 5.00 ) ( 4.00 ) ( 3.57 )	4.14

These Accounts agree very well with our best Charts, from which the Coast is here laid down; except 10' in C. Hinlopen.

The strong Currents, however, must make the Longitude of the Coast of Carolina very uncertain, as we see by the Reckonings to Charles Town. By pretty good Accounts in these Ships the Current from Georgia to Cape Henry, sets N.E. ¼ N. 9 Leags. in 24 hours in the Offing. In Soundings it sets N.E. by N. All along shoar [sic] from Cape Henry to C. Canaveral it sets Southerly, by several Observations. It sets Southerly again by Accounts 60 or 70 Leags. from Land in Lat 32° & 33°. Journ. Ships of War.

From C. Charles to C. May. Capt. Fane Surveyed the Coast 1605-6, lying N.N.E. & S.S.W. the whole way, the Current setting both North & South, like an Eddy, and N.W. into Delaware Bay, where it ends.

In the Northern Seas we have no such good Accounts of the Currents and Navigation, nor Reckonings of the Longitude. The Strong Currents about C. Race, Cape Breton & Canso make the Longitude of C. Race, if not of C. Sable, very uncertain. Some Observe a Current the whole way from Canso to St. George's Bank in Lat. Obs. 41°.54'. Setting S.W. 9 or 10 Ms. an hour; and a strong one off Chebucto. The Tides of St. Georges Bank, and the strong Tides into the Bay of Fundy are well know[n].

As the Coast is bold in these Northern Seas, they Observe many Bearings and Distances of Places along Shore, which if justly taken would determine their true Situation more nighly than any thing. It is from such Observations that all Charts & Maps are (or should be) made, which it is to be feared, ours in America are deficient in. Hence I have been at the tedious pains to Calculate the Latitudes & Longitudes to each bearing & Distance observed in our Ships of War, taking the mean of several Observations as above, and allowing the Variation here set down to each. These Bearings & Distances appear from the diff. Lat. & Longt. which we could only set down here. The way to Correct these Observations both on the Coast, and within Land, is, to take the Latitudes of Places whose bearing can be Observed; which two will give their true distance & Diff. Longt., and that more nighly than by the tedious and Expensive method of Mensuration that is only used.

From Segwin I. to Holt I. Champlain makes it E.S.E. i.e.: E. ½ S. 20 Leags. Our Draughts make it E.N.E. & E. b[y] N. from 12 to 24 Leags. which is very uncertain, as we have no Observaions any farther here from Boston.

From C. Sable to Long I. our ships make 25' diff. Longt. and 48' from C. Negroe. So Long I is 15 Leags. from Seal Is. by Accts. which being equal to the diff. Lat. they must both be nighly in the same Longitude.

From the West End of Long I. to the Et. End Grand Manan I. is N 41° W. 10 Leags. or 29 Miles, by Observations in several Ships. Thence to Mt. Desart I. they make S. 70°.30'. W. or W.N.W. 16 Leagues. Hence Mt. Desart I. is in Lat 44°.20' or 22' (agreeable to Richer) and but 20, or 21 Leags. from Long I.

C. St. Mary's is S. 62° E. 12 Ms. from Long I. by several Observations. From C. St. Mary's to C. Fourchu, there is no remarkable place but two small inlets. Fourchu or Fork Harbr. is at the Cape, and but 6 Leags. from Seal Is., and 4 Ms. from Tusket Riv &c. Hence the C. Sable Coast is very different from what our Maps make it, which place C. Fourchu in the upper, instead of the lower parts of the Coast, or make two Capes, by the name of C. Fork, C. Porceu Bursue &c. which are all Synonyma of C. Fourchu, properly called Cape Horn in our Language. vid. Journ. Albany; Champlain; Denys &c.

These Latitudes agree with the Lat. Obs. by Morris in the Bay of Fundy, and make Bay Verte 30' or 40' Lat. more South than former Maps. Hence the Peninsula of Nova Scotia is a Degree of Longitude, and half a Degree of Latitude less than is generally supposed.

If we make St. Pauls I. in Longt. 59°.50', with Chabert, that will make it too nigh C. Rosiers, or make C. Rosiers too nigh

Column L6

Quebec by these and all other Accounts, which make C. Gaspee N. 54° Wt. 60 Leagues from St. Pauls I. So in the Comet 1748 they Observed the Latitude of Labrador Entrance 46°.31'. In 1711, our Fleet lay in Spanish River and make it in Lat. 46°.24' by a good Observation in the Enterprise. In the Sapphire they took the Bearings of Spanish River very particularly, and make C. North bear from it N.N.E. At the same time (1711), they Observed the Variation in the Leopard by several Amplitudes 16°.30' West. Whence C. North bears from Spanish R. N. 6° E. But Mr. Chabert makes it bear N. 5° or 6° Wt. and makes St. Anne's by observation in Lat. 46°.21' to the Southward of the Observations both at Labrador & Spanish Rivr. There is a difference here then of a whole point of ye. Compass in the Bearing, and of 10 or 12 min. Lat. in positive Observations, which makes a Considerable mistake on one side or other. We cannot tell which. But as these Observations in our Ships agree with all our Draughts both French & English, we have let them stand till farther Information. Altho, St. Annes is perhaps farther South.

But from the Observations of Chabert, and others at C. Sambro, it appears that by Chebucto Harbr., our people mean Chebueto Head, which is not in their Plan, but 10 Ms. South of the Harbr. at Halifax, which by this must be in Lat. 44°.40' or 41'. These Latitudes with the above distance make 47' diff. Longt. between Halifax & Minas.

But in our new Maps copyed [sic] from Chabert, they follow these Latitudes without any regard to the Longitude, (as is usal with Map-makers) and thereby make Halifax but 25 Ms. from Minas, instead of 3g; and the road from Halifax to Pesaquid but 30 Mls instead of 46.

By this Chebucto is nigher Canso than C. Sable, agreeable to Durell's Survey and an Observation of the Longitude by Chabert, which makes this Coast 57' farther East than he lays it down from his Reckonings; which being implicitly copyed [sic] in our New Map, they make C. la Heve but 24 Leags. from C. Sable, which Durell makes 32 Leags. &c. The true distances here are perhaps uncertain from Sea Reckonings, on Account of the Tides or Currents observed.

By this the Head of Kenebec R. will be in Lat. 45°.36', that is 80 Ms. or 92 Mls from the Lat. Obs. of Quebec; whereas by all Accts. they are but 60 mls. asunder. If we make Quebec farther West, their distance would be still greater. But it appears from many other things, that this (pretended) Survey, as it is published, is not to be relyed on.

Column L7

Longitude of Hudson's Riv:, to determine the Longt: of the Coast of New England from thence. But as nigh as we can judge, it appears doubtfull from hence, whether Boston is in Longt. 70°.45', 70°.52' or 71°, as different observations of Hodgson & Robie make it, altho it is certain from hence, that it cannot be in 70°.30', nor 71°.30', as we are told from false accounts of these observations.

The Reckonings of Gist in his Journals from Ft. Cumberland make Ft. du Quesne in Longt. 80°.15'. The mean of these two accounts is 79°.47', which we followed. But allowing for Heights of Mountains &c Ft. du Quesne is not farther West than 79°.30' at most: which makes it 189 Ms. from Philadelphia; 255 from C. Henry; 253 from New York; 248 from Sandy Hook, the nighest Part of the Coast; & 47 from Ft. Cumberland.

2. From Smith's Point to Ft. Cumberland by the Surveys of Potowmack Riv: N. 48° W. 160 Ms. (or 157 Ms.), makes diff. Lat. 1°.47': diff Longt. 2°.32' and Ft. Cumberland in Lat. 39°.42': Long. 79°.6'.

These Latitudes are a mean between the Surveyors for the Crown and Proprietor, who differ 15 Min. in the Lat.of Potowmack River.

3. From Cresson's nigh Ft. Cumberland to the Falls of the Ohio, the Courses & Distances were carefully observed by Gist in his Journals to every 4 or 5 miles: to each of which I have calculated the Latitude & Longitude, making the proper allowances, and from thence we have the Situation of the following Places:

 

	Lat. D.M.	Lon. D.M.
Ft. du Quesne	40.26	70.30
Loggs Town	40.30	80.00
Muskingum (in all which we allow for a crooked uneven Road)	40.26	81.55
Shannoah	38.41	83.23
Falls of Ohio	37.20	84.59

This we see agrees surprisingly well with the Longitude of the Missisipi determined by the observations at N. Orleans, altho uncertain.

4. By a grosser Estimate of Gist. Pickawillany, Hockhochen, & L. Erie should be 30, or 40, Min: of Latitude farther South, than Charlevoix's Acct. of the Entrance of Detroit being in Lat. 42°.12' or 15' seems to make them. So Niagara is supposed to be in Lat. 43°; which would make L. Erie too nigh the Ohio, according to our accounts of the Distance between them; which however appear uncertain. Sandoski is 80 Mls. from the Riv. Miamis by Accounts of those that have gone it; others make that & Gwahago farther West.

By the Longitudes here observed, the Breadth of the Continent from C. Henry to the Missisipi is about 620 or 630 Ms. And 557 Ms. from Charles Town to New Orleans.

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