ANTIQUE KEUFFEL & ESSER THACHER\'S SLIDE RULE #4012 CALCULATOR
When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
ANTIQUE KEUFFEL & ESSER THACHER\'S SLIDE RULE #4012 CALCULATOR:
$600.00
Up for your consideration a Thacher\'s Calculating Instrument (TCI)mfg by Keuffel & Esser Company, New York, Hoboken, NJ. Model 4012, Serial # 5668, believed to be 1930 ± several years vintage.
Patented by Edwin Thacher, C.E., Nov 1st 1881.
A scales on internal cylinder clean, clear and legible.
B,C scales on external cylinder clear to moderate foxing, allnumbers and grids are legible. (Foxing: age spots caused by corrosion of metallic triangular supports for B,C scales attached thereto; most TCI\'s in existence suffer some degree of foxing, from moderate to complete obliteration of graphics.)
Internal cylinder rotates and slides in-out smoothly. External cylinder rotates smoothly.
TCI is equivalent to a linear slide rule about 30 feet in length; 4 to 5 digit results from computation are routine.
Introductory operating instructions located on base of instrumentare complete and legible.
The booklet Directions for Using is included. Cover of this booklet is detached, but otherwise in excellent condition. Good bedtime reading.
ANTIQUE KEUFFEL & ESSER THACHER\'S SLIDE RULE #4012 CALCULATOR:
$600.00