Presented is an ebony frame, ivory arc, antique sextant
by the British instrument maker, G. Heath, London. It looks like it has been preserved in a time capsule
and never used. Most all the brass was finished with a swirl pattern which is highly unusual for an instrument of this
period and is why we believe it made for a special purpose.
G. Heath was in business during the mid 19th Century and may be related to
the more famous Thomas Heath firm, and its predecessors. G. Heath is listed in Webster’s Registry of Instrument makers.
The original Thomas Heath firm’s operations date back to 1720 when Thomas Heath, the elder, began making instruments
on the Strand in London. Many people associated with the family firm went on to become prominent instrument makers on
their own. Such men as Throughton, and Watkins worked there for a time before establishing their own shops. In 1845 Thomas
Heath, II took the helm and the firm’s name was changed to Heath & Co., and it continued in business until the mid 20th
Century. The Heath three ring design Hezzanith sextant is likely the most numerous ever produced, and can still be found in
great quantity today.
There are very few of G. Heath instruments known to exist and nothing is known
of the maker’s history other than he is listed in Webster’s Database of Instrument Makers. A similar
example of this instrument may be seen at theLadd Observatory,
Brown U., Providence, R.I. There also is a picture of a similar instrument and reference in the book Nautical Antiques
by Robert W.D.Ball, page 139, Schiffer Publishing, Atglen, PA 19310, (C) 1994.
This octant dates from the mid 19th Century. Except for a very few
exceptions, it is in outstanding condition with all its metal machinery, and sharply engraved ivory in place. Rarely
seen with instruments of this age, is the small ivory plate on the backside and the ivory cap for a lead pencil to record
the reading of the observations.
The arc measures from – 5 to plus 105 degrees. The ivory plate on a cross
bar between the two limbs is engraved “G. Heath London”.
The sextant has a ribbed brass index arm measuring 12 inches long
with a diameter of arc of 9 3/4″. The horizon mirror is on an adjustable turntable and can be rotated by a horizontal
knob and locked in position by another knob on the sextant’s reverse. There are three rectangular sun shades for the index
mirror, but none for the horizon mirror. Note the early form ivory vernier scale, reading from right to left from
0 to 20 arc minutes, two hole peep sight with “flap”, and only three sun shades all of which help date the instrument. There
is no provision for a handle on this instrument which marks it as a transitional piece between an octant and a sextant.
Some time after 1780, the addition of a tangent screw, as fitted
to this instrument, allowed for fine adjustment and represents one of the two major changes in the basic operation of the
octants and sextants for the next 150 years! The second was the fitting of telescopes. As was the practice with octant’s of this
size, this sextant was not fitted with a handle which indicates it is one of the earliest of that type made.
INSTRUMENT CONDITION: The sextant is in excellent condition
and looks like it sat on a shelf somewhere and never used. The horizon mirror has no corrosion and only a few
age cracks. The index mirror has a dark “T” in its center, but is completely useable. All the ivory is in perfect condition,
and the engraving is sharp and distinct. The index arm clamp’s screw works freely. The tangent screw and other adjustment
knobs work, and the shade glasses are complete and in good working order. The ebony frame shows as near new except for a small
imperfection where the cross member meets the frame on the right. The instrument has its original machinery, an adjustment
wrench and a two hole peep sight. Everything is original and in good working order and this instrument rates 5 Stars.
THE SEXTANT’S CASE: The sextant is housed in a keystone
case, complete with no key. It has two age cracks on its bottom right corner and a chip missing at the top
right, but is good and sturdy. Somewhere in the past, the top of the case was sanded across the grain and the case was refinished.
It has some water stains inside, but otherwise is clean. There is no label.
Maker’s Name
Vernier scale
Shades
and index mirror
Peep sight and horizon mirror
SEE MORE PICTURES IN THE GALLERY BELOW
All in all,
a highly desirable and worthwhile example from one of the lesser known English instrument makers.
DIMENSIONS:
Length of frame 12″
Width of frame at arc 9 3/4″
Index mirror 48 x 32 mm
Horizon mirror 27 x 23 mm
Weight 2 Lbs 5 oz
OUR CREDENTIALS: We are one of the few people selling
Old World navigation instruments that know anything about them. For purposes of judging whether my opinion counts, I was the
editor of the chapter on sextants of the 1977 Edition of “Bowditch”, The American Practical Navigator, NAVPUB 9; a member
of the U.S. Naval Academy Navigation Symposium Board, 1975-1978; the author of a book on marine sextants, Cornell Maritime
Press,1975, and the founding president of Nautech Maritime Corporation which partnered with Tamaya of Japan in the introduction
of the MS 733 Spica, the MS 833, Jupiter, MS 933 Venus sextants and the famous NC-2 navigation computer, in the U.S. market.
I am also a retired Master Mariner, and formerly held a U.S. Navy “D” Qualification as a Senior Skipper – Oceans.
Rarely do you find a special instrument that
is that is 157 years old in this original condition with its original. A superior
addition to any collection.
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