etui of 9 drawing instruments
Date: 1775-1800
Inventory Number: 5458
Classification: Etui
Dimensions:17.5 x 7 x 3 cm (6 7/8 x 2 3/4 x 1 3/16 in.)
Accessories: case contains the following nine instruments: one ivory and brass sector; one ivory and brass parallel rule; one brass protractor; two pairs of dividers, one with pen holder, pencil holder, and inking wheel (for drawing dotted line) attachments; and pen.
DescriptionThis etui is made of wood covered with paper and black sharkskin. The framing is brass as is the button catch. The top is lined with Dutch gilded paper. The instruments in the etui are brass and ivory. They include:
(1) semicircular protractor
The brass protractor has divisions every 1° from 0°-180° in both directions.
(2) parallel rule
Made of two ivory rules linked by brass brackets. Two brass knobs. On underside is a diagonal scale for precision measurement and scales of equal parts for 30, 35, 40, and 45.
(3) sector
This is an English sector engraved with the following scales:
side a:
line of chords ("Cho")
line of natural secants ("sec")
line of lines ("Lin"), also known as line of equal parts
line of polygons ("Poll")
small line of natural tangents ("Tan")
small line of sines ("Sin")
Gunter's line of numbers ("Num")
side b:
line of natural sines ("Sin")
line of natural tangents ("Tan")
small line of natural tangents ("tan")
scale of equal parts 1-100
along outer edges of arms:
scale of inches, 1-12
The sector hinge is round and plain. There are retaining pins between the arms.
(4) dividers
Brass dividers with flat hinge and steel points. One leg is designed to accept alternative inserts. It currently has a steel point.
(5) ruling pen insert
Jointed brass insert with steel blades and knurled screw to hold ink. This goes with the dividers above to turn them into a drawing compass.
(6) pencil / crayon insert
Jointed brass insert with holder for graphite or crayon.
(7) dotted-line pen insert
Jointed insert with brass toothed wheel to ink dotted lines.
(8) small dividers
Brass dividers with steel points.
(9) ruling pen
A turned brass column is attached to steel blades with a knurled screw to hold ink.
An empty slot in the case shows that one tool is missing.