FINE COMPLETE & UNTOUCHED CONDITION HENDERSON DIAL BY JOHN TEAGUE LETCHER OF TRURO CORNWALL

FINE COMPLETE & UNTOUCHED CONDITION HENDERSON DIAL BY JOHN TEAGUE LETCHER OF TRURO CORNWALL

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EXTREMELY RARE LATE 19TH CENTURY MINING THEODOLITE SIGNED: HENDERSON DIAL. MAKER J T LETCHER. TRURO CORNWALL. THE DIAL IS AN IMPROVEMENT ON THE WELL KNOWN LEAN DIAL HAVING HAIRLESS SIGHTS NOT PRONE TO CANDLE DAMAGE! IT HAS FOUR SIGHTS FOR THE HORIZONTAL CIRCLE. THE 6" INCH SILVERED DIAL HAS A INNER CIRCLE OF FOUR 90 DEGREE QUADRANTS DOUBLE VERNIERS READING TO 2 MINUTES OF ARC. THE OUTER 360 DEGREE CIRCLE READS WITH NEEDLE VERNIER TO 1 MINUTE OF ARC. THE SILVERED COMPASS HAS EAST & WEST TRANSPOSED. IT HAS VERTICAL INVERTED HALF CIRCLE CARRYING A OPTICAL TELESCOPE WITH SHORT & LONG EYEPIECES GIVING INVERTED & ERECT IMAGES, ALSO INTERCHANGABLE SHORT SIGHTS FIXING TO THE Y MOUNTS, READING WITH VERIER TO 1 MINUTE OF ARC. THE DIAL WAS USED WITH THREE TRIPODS, PLEASE NOTE THE THREE SETS OF THREE POINTS FOR LOW SEAM WORK. TWO DIAL POSITIONS & ONE FOR THE CANDLE SIGHT. THE DIAL CAN BE USED AS A THEODOLITE, CIRCUMFERENTOR OR SIMPLE MINING DIAL.

Circa

1870

Country of manufacture

UK and Ireland

Category: Surveying Instruments & Mining

Description

THE DIAL & ACCESSORIES COME IN TWO MAHOGANY BOXES WITH ORIGINAL LEATHER OUTER CASES. THE LARGER BOX IS BRASS BOUND 11.1/2″ x 11″ x 6″ INCHES. THE SMALLER  BOX WITH THE THREE 4 SCREW MOUNTS & CANDLESTICK 9.1/2″ x 8″ x 6″.  INVENTER: CAPTAIN ( ROYAL ENGINEERS ) JAMES HENDERSON M. OF INST C. E. TRURO. HIS IMPROVED LEAN DIAL Ca. 1869. HE ALSO INVENTED HIS RAPID TRAVERSER IN 1892. JAMES HENDERSON 1821-1903. MAKER: JOHN TEAGUE LETCHER WAS APPRENTICE TO WILLIAM WILTON JUNR. IN JUNE 1863 AGED 12 YEARS. WILTON SOLD UP IN 1867 TO MR A JEFFERY OF CAMBORNE WHO TOOK OVER FOR THE NEXT TEN YEARS. JOHN LETCHER CONTINUED HIS APPRENTICESHIP WITH EDWARD TIPPET NEWTON WHO HAD MARRIED WILLIAM WILTON SENIOR’S DAUGHTER. THE COMPANY THEN BECAME LETCHER BROTHERS & JEFERY. BY 1878 THE LETCHER BROTHERS MOVER TO CATHEDERAL LANE TRURO. THE COMPANY THEN BEING J T LETCHER. LETCHERS WERE ALSO FAMOUS FOR THERE SOCIETY OF ARTS BLOWPIPE SETS. THIS IS A RARE & HISTORICALLY IMPORTANT INSTRUMENT IN MINE SURVEYING, AS FAR AS I CAN REMEMBER THIS IS THE ONLY HENDERSON DIAL I’VE EVER HAD, I DID HAVE A TRAVERSER 30+ YEARS AGO. DELIVERY UPS FULLY TRACKED.                                                            Contact Email: m.jread@btinternet.com

 

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GB MikeRead

Mike Read Antique Sciences

Based in Lelant, near St Ives, Cornwall, I have been trading since 1979, buying and selling scientific instruments and nautical antiques. I have exhibited at the London Scientific Fair for 20 years. Over the years I have acquired many rare and wonderful items for the trade and collectors alike. I hope this continues. Mike Read. Email: m.jread@btinternet.com.

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