A treatise on mathematical instruments, including most of the instruments employed in drawing, for assisting the vision, in surveying and levelling, in practical astronomy, and for measuring the angles of crystals: in which their construction, and the methods of testing, adjusting, and using them, are concisley explained

Heather J. F. (John Fry) D. 1886

Description

UC-NRLF B H EMT Ebfl '?•. 32. T R E A/1' i /*> &**£*£ i VTH?M A/JTCAX INSTRUMENTS. i :. J". AIIFaTHEI George Davidson Professor of Geoj-raphy of CalifofniUniversity AJ s± ; but, if the points r> and e be opened to the&c. lengths of the lines upon a drawing, the points a and b will prick offacopy with thelines enlarged to to 4 toin the proportions of 2 1, 3 1, 1, &c. To inscribe in a Circle a regular Polygon of Sides C to 20.—The lineany number of from across the slider being set to any number on the scale of circles,and the points a and b beingopened to the length of any radius, the points d and e will prick off a polygon of that number of sides, in the circle described with this radius ; thus, if the line across the slider be set to the division marked 12 on the scale of cir- circle be described with the radius a d e willcles, and a. b, be the chord of a -Jgth part of the circumference, and will prick off regular polygon of 12 sides in it.a To reduce or enlarge theArea a Drawing.—The numbersof upon the scale of plans are the squares of the ratios of the lengths of the opposite ends of the compasses, when the line across the slider is set to those numbers ; and, the distances lengthsbetween the points being in the same ratio as the of the corresponding ends (Euc. vi. prop.

Sujets

• Measurement
• Surveying
• Instrument
• Mathematical instrument
• Optical instrument

Informations

• Publié par: les_archives_du_savoir
• Nombre de lectures: 8
• Langue: English
• Poids de l'ouvrage: 10 Mo

Extrait

and e be opened to the&c. lengths of the lines upon a drawing, the points a and b will prick offacopy with thelines enlarged to to 4 toin the proportions of 2 1, 3 1, 1, &c. To inscribe in a Circle a regular Polygon of Sides C to 20.—The lineany number of from across the slider being set to any number on the scale of circles,and the points a and b beingopened to the length of any radius, the points d and e will prick off a polygon of that number of sides, in the circle described with this radius ; thus, if the line across the slider be set to the division marked 12 on the scale of cir- circle be described with the radius a d e willcles, and a. b, be the chord of a -Jgth part of the circumference, and will prick off regular polygon of 12 sides in it.a To reduce or enlarge theArea a Drawing.—The numbersof upon the scale of plans are the squares of the ratios of the lengths of the opposite ends of the compasses, when the line across the slider is set to those numbers ; and, the distances lengthsbetween the points being in the same ratio as the of the corresponding ends (Euc. vi. prop." />

UC-NRLF
B H EMT Ebfl
'<>?•. 32.
T R E A/1' i
/*> &**£*£
i VTH?M A/JTCAX INSTRUMENTS.
i :. J". AIIFaTHEIGeorge Davidson
Professor of Geoj-raphy
of CalifofniUniversityAJ<uas*M*u;Murrey^trr^
4:
v^
TREATISE
INSTRUMENTS,MATHEMATICAL
INCLUDING
INSTRUMENTS EMPLOYED IN DRAWING,MOST OF THE
IN PRACTICALASSISTING THE VISION, IN SURVEYING AND LEVELLING,FOR
AND FOR MEASURING THE ANGLES OF CRYSTALS:ASTRONOMY,
IN WHICH
CONSTRUCTION, AND THE METHODS OFTHEIR
ADJUSTING, AND USING THEM,TESTING,
ARE CONCISELY EXPLAINED.
F. HEATHEK, Ml.BY J
MILITARY ACADEMY, WOOLWICH.OF THE ROYAL
EDITION,THIRD
CORRECTIONS.WITH
LONDON
JOHN WEALE, 59, HIGH HOLBORN.
1856.LONDON :
BRADBURY AND EVANS, PRINTERS, WHITEFRIARS.QA7/
PREFACE.
has been made in the following pages to putAn attempt
reach of all a short and compendious treatisewithin the
ingenious instruments by which theupon some of the
is aided in his observations, and in thescientific practitioner
obtained from them.delineation of the results
treated of have been divided into fiveThe instruments
part of the work has been devoted.classes, to each of which a
Mathematical Drawing InstrumentsThe first part treats of ;
Optical Instruments ; the third, of Surveyingthe second, of
Astronomical Instruments andInstruments ; the fourth, of ;
Goniometrical Instruments, for measur-the fifth, and last, of
ing the angles of crystals.
Engravings, and some partsThe greater part of the Wood
Drawing Instruments,of the Text, of Simms's Mathematical
work andhave been pressed into the service of the present ;
parts of thethe works of the best writers upon the several
hassubject have been consulted, and much valuable matter
Astro-been extracted from them, particularly from Pearson's
nomy.
forbiddenThe limits of the bulk and cost of the work have
the instru-any extensive excursion into the sciences in which
of informa-ments are used ; but it is hoped that a large mass
tion has here been placed in a small compass without sacri-
ficing perspicuity to undue compression
R. M. A.
March, 1849.
M520000