Old Hampshire Mapped
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.|
The title cartouche of Ogilby's plate 30 has cherubs holding surveying instruments.
The frontispiece to Ogilby's volume includes pictures of surveyors at work.
A header to the preface to Ogilby's road book has cherubs holding instruments.
A preface page to Bowen's road book has cherubs holding instruments.
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.
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.
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.
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 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.
- 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.
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.
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.
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.|
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.
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.
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 ...
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.]
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
||Old Hampshire Mapped|