Presented is a contemporary three ring bronze frame sextant by the British
instrument maker, Heath, & Co., LTD, New Eltham, London. The instrument has its original certificate dated 24 June 1971 which matches its serial number of 71350. It has served at sea which shows in the wear to its case, but the instrument is in overall excellent condition. It is fitted with a low power and wide field of view star scope which is also good for all-around use. The telescope is mounted on a fixed arm called a rising piece.
The arc measures from – 5 to plus 125 degrees. It is read by micrometer drum with tangent screw off a vernier reading to 10 arc seconds. A quick-release mechanism at the end of the arm engages with worm teeth cut on the underside of the limb. This mechanism, marked “‘HEZZANITH’ ENDLESS TANGENT SCREW AUTOMATIC CLAMP PATENT facilitates making fine adjustments. The original British patent for this lever was issued in 1909.
BRIEF HISTORY OF MAKER: The Heath name was synonymous with quality from the earliest days of the London scientific instrument trade. The Thomas Heath firm, and its predecessor’s
operations date back to 1720 when Thomas Heath began making instruments on the Strand in London. Many people associated with the family firm went on to become prominent instrument makers in their own right. Such men as Adams, Troughton, and Watkins worked there for a time before embarking on their own. 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 frame design Hezzanith sextant is likely the most numerous ever produced, and can still be found in great quantity today.
INSTRUMENT CONDITION: Except for a very few minor cosmetic exceptions, it is in outstanding condition with all its metal machinery in good working condition, and only shows minimal wear. The horizon and index mirrors are in like new condition.
The manufacture did not provide illumination on this model.
The index arm clamp works freely, and the tangent screw moves as
it should. The shade glasses are complete and in good working order. The midnight black wrinkled finish bronze frame is in good condition except for some minor evidence of age in a few places. The instrument has four shades for it telescope which is clear and sharp. The original adjustment pick is missing, but a replacement is provided. The original inspection certificate is present, but we took some practice sights which, after tuning, worked to our satisfaction. Adjustable error is 1 minute off the arc index and there is no appreciable side error.
STAR RATING: Everything of the instrument is original and in good working order and this instrument should rate 5 Stars. It is ready to go back to sea.
THE SEXTANT’S CASE: The sextant is housed in a square case, complete, with a latch that is a recent replacement. The case is made out of a laminated plywood with a very thin outer veneer. Some of this is missing in a few places and some has delaminated. There are no age cracks, but there are holes drilled through the bottom which indicate this case was mounted on a bulkhead which is the practice of many navigators. There are some scratches and degradation of laminate, but the inside of the case is clean and fresh, and remains sturdy.
SEE MORE PICTURES IN THE GALLERY BELOW All in all, a highly desirable and worthwhile example from one of better known English instrument makers.
Telescope 4 x 26 est.
Length of index arm 9 1/8″
Width of frame at arc 9 1/4”
Index mirror 30 x 40 mm
Horizon mirror 30 x 45 mm
Instrument weight 3 lbs Total weight 8 lbs