Old Hampshire Mapped


Surveying

Notes
measuring NB: These are NOT comprehensive notes about surveying, just notes relevant to the Hampshire maps project, in particular to the road maps of John Ogilby, 1675.

Ogilby
plate 30

The title cartouche of Ogilby's plate 30 has cherubs holding surveying instruments.

Ogilby
frontis
-piece



The frontispiece to Ogilby's volume includes pictures of surveyors at work.

Ogilby
preface

A header to the preface to Ogilby's road book has cherubs holding instruments.


Bowen
preface

A preface page to Bowen's road book has cherubs holding instruments.


Taylor

The scale line on Taylor's map, 1759, is engraved on a stone block, a monumental sculpture with surveying tools and cherubs ... There is a globe atop, an alidade? dividers, plane table? chain, ruler? theodoliite? and lots of scroll work. One of the cherubs is ?drawing a map.


Chain
In Ogilby plate 30 the chain held by a cherub has only a few links, but is clearly a surveyor's chain.

In the frontispiece to Ogilby's road book there is a chain lying on the work table of the surveying team.

The chain is used for making linear measurements on the ground. A common surveyor's chain, in England, Gunter's chain, has 100 strong 'links' of wire connected by iron rings, with brass handles at the two ends. Intermediate points are marked by small brass tags at 10 link intervals. The usual length of Gunter's chain is 22 yards ie 66 feet, and measurements are made in chains and decimal parts which might be expressed in links; 3.34 chains = 3 chains 34 links. A link is 7.92 inches.

The chain is a decimal instrument, 1/100th chain is 1 link. The chain was introduced by Edmund Gunter, b1581 d1626, mathematician, who is also credited with the introduction of the decimal separator to mathematical notation.

Cross staff
- Groma
Seen side on, a cross staff might well look like the staff with a cross piece and three small uprights that is drawn in the cartouche decoration to Ogilby plate 30.

A cross staff is used by a surveyor for setting out long offsets at right angles from his chain line. At the top of a staff there are four arms with sight slits at right angles.

There is some confusion in nomenclature; the cross staff is perhaps better called by its roman name, a groma, or called a surveyors cross.

Protractor The instrument in the right cartouche of Ogilby plate 30 is a protractor, though it is not drawn with divisions.

Another protractor is lying on the table used by the survey team in the frontispiece to Ogilby's road book.

A protractor is a drawing instrument, a circle or semicircle marked into degrees and more or less minute divisions round its edge. Used for measuring or setting out angles on a drawing.

Dividers Dividers lie on the surveyor's table in the Ogilby frontispiece. And appear with the cherubs in Bowen's preface page.

Dividers are a drawing and measuring tool used for setting off distances.

Cross staff
- Jacob's staff
A cross staff lies on the surveyors' table drawn in the frontispiece of Ogilby's road book.

This is a graduated rod about 2-3 feet long with one or more sliders. It is used to measure the elevation of the sun, or other celestial body above the horizon.

Quadrant The quarter circle with a plumb bob attached on the surveyors' table in the frontispiece to Ogilby's road book is probably a quadrant used for measuring the elevation of the sun or other celestial bodies.

Although unclear it could be a quadrant held by one of the cherubs of the Bowen preface page.

Compass The compass hanging on a branch in the left cartouche drawing of Ogilby plate 30 looks like a small handheld magnetic compass in a neat square case.

A cherub in the header to the preface holds a compass with perhaps folding sights, perhaps a circumferentor? This might be hand held or mounted on a staff.

Another compass with sights is lying on the surveyors' table in the frontispiece to Ogilby's road book.

Simple theodolite Lying on the surveyors' table in the frontispiece to Ogilby's road book is what looks like a simple theodolite. This has a compass to align it, and rotating sights, an alidade, the direction of which reads off a scale.

Waywiser The waywiser was John Ogilby's favoured device for measuring distance. His preface extolls its virtues. It goes under various names, including perambulator and hodometer. It is not a pedometer or passometer: those instruments count paces.

The waywiser has a wheel, which is trundled along the route, whose revolutions are counted on a dial; correctly geared the dial pointer can display distances in yards, furlongs, miles, whatever. A motorcar mileometer performs much the same task.

The frontispiece to Ogilby's road book shows a man trundling a waywiser.

If you keep your eyes open today you will see highways surveyors using a waywiser, with a small wheel whose circumference is probably one metre.

Measuring John Ogilby 1675, in the preface to the road book:-
... a Word or two of Dimensurators or Measuring Instruments, whereof the mosts usual has been the Chain, and the common length for English Measures 4 Poles, as answering indifferently to the Englishs Mile and Acre, 10 such Chains in length making a Furlong, and 10 single square Chains an Acre, so that a square Mile contains 640 square Acres; This, as it obliges the Surveyor to chargeable Assistances, so it exposes the Account to the Dangers of Mistakes, which, perhaps is not the least Reason of the slow Progress of Actual Dimensuration, even in these last Centuries; That We have been much facilitated therefore in this Great Work by the Wheel Dimensurator, which, for Ease and Accurateness infinitely surpasses the Chain, as being manageable by a single Person, Measuring, even the smallest Deviations of the way, and finishing a Revolution but once in 10 Miles; We readily acknowledge, and even in Wheels themselves, commend rather the Foor-Wheel here mention'd, of half a Pole Circumference, with the Way-Wizars as they are now Regulated, than any such like Coach or Chariot-Mensurator whatsoever.

... the Direct Horizontal Distance, by which We understand the nearest Interval between the two Places, which We have cursorily Collected from the Horizontal Protraction of the said Roads, with convenient Deductions for the several Hills and smaller Deflexures of the Way: And upon these two Points, with the included Difference in Heavens, depends that necessary Investigation of the Quantity of a Degree upon the Superficies of the Earth, ... Fernelius by the Revolutions of a Wheel, 68 Italian Miles and 96 Paces; Our Mr. Norwood in his Experiment from YORK, more than 69 Miles and an half; the Learned Mr. Oughtred about 66 Miles and a quarter; the Accurate Mr. Picart above 69 Miles, vis. 57064 Toises of Paris of 6 Foot, equal to 365'184 English Feet, and the Vulgar Computation only 60 Miles: This, if accurately adjusted, (and We hope much, even from Our own Dimensurations) would conduce infinitely to Regulation of Latitudes and Longitudes: In the first of Which, some have deviated more than a whole Degree in the Position of Barwick, and others 3 or 4 Degrees in the later, in Asserting the Distance between the Lands-End and North-Foreland.

Thirdly, The Vulgar Computation, which (though variously accounted) We have thought fit should also accompany the Dimensuration, by the Inequality of which, the Peruser may easily observe the Erroneous and Irregular Consequencies necessarily following a Dependance thereon, which, in some Parts near equals, in others, answers only 3 quarters, and sometimes but Two Thirds of the Dimensuration; ... Now whence these Computations arose is altogather uncertain, the nearest Conjecture is, that they seem to excludde the whole Length of the Towns, and to be the Distance from the End of one Town to the Beginning of the Next, not regarding the Fractional Parts of a Mile, but taking the lesser Integer, which in a well inhabited Road will come near the Matter.

Not all surveyors were surveyors. Edward Worsop, 1582 in Discoverie of Sundrie Errors and Faults Daily Committed by Landemeaters wrote:-
[Every one that measureth Land by laying head to head, or can take a plat byb some Geometricall instrument, is not to be accounted therefore a sufficient Landmeater, except he can also proove his instruments, and measurings, by true Geometricall Demonstrations ...

Everie man knoweth that lande is our riches in the hyest nature, and yet true surveying, and valuing thereof is shoufled up, as though it were a matter of small importance ...]

Ralph Agas, 1596, in Preparative to Platting of Landes and Tenements for Surveigh quotes from his own experience:-
[And in my coming to London, this last Tearme, I saw a plaine Table man (mary he was a plumber, and had learned from a Painter) in lesse than an acre and halfe of levell marrish grounde taken by some foure stations fel short at his cloase two perches at the least ...]
Agas comments on plain table and theodolite:-
[Twentie and five years past or there abouts I used the said table, sometime directed by needles, sometime by the former Station, as is nowe used, sometime in the middle of the close, sometime by the bounders &c. I consider hir defectes, neglected the same, and tooke me wholly to thee Theodolite, whereupon, I have ever since practised, to the daily increase of my liking, as well as for perfection, and expedition, as for the infinite and rare uses thereof, being accordingly prepared.]


References Agas, Ralph: 1596: Preparative to Platting of Landes and Tenements for Surveigh: (London?)

Emmet, Boris (ed): 1969 (reprint) & 1895 (original): Montgomery Ward and Co Catalogue and Buyers' Guide: Dover Publications (New York, United States):: ISBN 0 486 22377 9

Lucar, Cyprian: 1590: Treatise named Lucarsolace, A: (London):: describes surveying instruments; BritLib C.114.e.4

Michel, Henri; Maddison, R E W (trans); Maddison, F R (trans): 1966 & 1967 (trans): Scientific Instruments in Art and History: Barrie and Rockliff (London)

Norden, John: 1607: Surveyors Dialogue, The: (London): BritLib C.113.b.16

Whitelaw, John: 1929 (8th edn): Surveying as Practised by Civil Engineers and Surveyors: Crosby Lockwood and Son (London)

Worsop, Edward: 1582: Discoverie of Sundrie Errors and Faults Daily Committed by Landemeaters: (London):: BritLib 967.k.23


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