An illustration showing how to construct an isometric ellipse by compass and six circle arcs. "Divide OA and OB each into three equal parts; draw the quadrant AC. From C, draw the line Cc through the point 1. Through the points 2 draw de at an angle of 45° with the major axis. Then 2 is the center for the ends of the ellipse; e is the center for the arc dc; and C is the center for the arc cf."

Construction Of An Isometric Ellipse

An illustration showing how to construct an isometric ellipse by compass and six circle arcs. "Divide…

An instrument which could more readily adapt itself to the swaying of the observer's body in a sea-way, soon displaced in good measure the astrolabe on shipboard. It in several ways modified forms for a long time served mariners as a convenient help in ascertaining the altitude of the celestial bodies. Precisely when it was first introduced is not certain; but the earliest description of it which has been found is that of Werner in 1514.

Jackstaff

An instrument which could more readily adapt itself to the swaying of the observer's body in a sea-way,…

Lengthening bar is used to draw circles bigger than 10 inches.

Use of Lengthening Bar

Lengthening bar is used to draw circles bigger than 10 inches.

If a magnetized bar or needle be suspended at its centre of gravity so as to move freely in a horizontal plane, after a few oscillations it will come to rest, with one of it ends pointing nearly to the geographical north pole of the earth.

The Magnetic Needle

If a magnetized bar or needle be suspended at its centre of gravity so as to move freely in a horizontal…

A tool used for navigating

Navigation

A tool used for navigating

"Bring the two ends of the wire into contact, and thus close the circuit. The needle instantly flies around as though it was trying to place itself at right angles to the wire. Break the circuit, and the needle swings back to its north and south position. Twist the wires together, and bend the conductor into a loop so that the current passes above the needle in one direction and beneath the needle in the other direction. The deflection of the needle will be greater than before." — Avery, 1895

Needle, compass

"Bring the two ends of the wire into contact, and thus close the circuit. The needle instantly flies…

Draftsman's first method for drawing a parabola

Parabola First Method

Draftsman's first method for drawing a parabola

This bow pencil is used to make small curves.

Bow Pencil

This bow pencil is used to make small curves.

The bow pencil is used to draw small circles and arcs.

The Bow Pencil

The bow pencil is used to draw small circles and arcs.

"A circle may be shaded by shifting the center on a 45-degree line toward the lower right hand corner... by keeping the needle in the center after drawing the circle and springing the compass out and gradually pressing with the middle finger in the position as shown." —French, 1911

Shading a Circle Using Compass

"A circle may be shaded by shifting the center on a 45-degree line toward the lower right hand corner...…

"A slender length of brass resting in a small brass button and designed to stand vertically on the center of a compass glass. From the shadow cast by it the sun's bearing is determined. It may also be used to take compass bearings of other objects." -Whitney, 1911

Shadow Pin

"A slender length of brass resting in a small brass button and designed to stand vertically on the center…

Still life arrangement including a globe, telescope, book, right angle, rolled map, and dividers.

Still Life with Globe and Telescope

Still life arrangement including a globe, telescope, book, right angle, rolled map, and dividers.

"Draw a circle three inches in diameter. Divide the circumference into five equal parts by trial with dividers. From these points draw radial lines and divide each into four equal parts with spacers. With these points as centers draw the semicircles as shown The radial lines are not to be inked." —French, 1911

Drawing Tangent Arcs with Compass and Dividers

"Draw a circle three inches in diameter. Divide the circumference into five equal parts by trial with…

"On base AB, 3 1/2" long construct an equilateral triangle, using the 60-degree triangle. Bisect the angles with the 30-degree angle, extending the bisectors to the opposite sides. With these middle points of the sides as centers and radius equal to 1/2 the side, draw arcs cutting the bisectors. These intersection will be centers for the inscribed circles. With centers on the intersection of these circles and the bisectors, round off the points of the triangle as shown." —French, 1911

Drawing Tangent Circles and Lines with Compass and Triangles

"On base AB, 3 1/2" long construct an equilateral triangle, using the 60-degree triangle. Bisect the…

Draftsman's method to draw a tangent, AB, to a circle

Tangent To A Circle

Draftsman's method to draw a tangent, AB, to a circle

"Draw one and one-half inch square about center of space. Divide AE into four 3/16" spaces, with scale. With bow pencil and centers A, B, C, D draw four semicircles with 3/8" radius and so on. Complete the figure by drawing the horizontal and vertical tangents as shown." —French, 1911

Drawing Tangent to Circle Arcs with Bow Compass

"Draw one and one-half inch square about center of space. Divide AE into four 3/16" spaces, with scale.…

Draftsman's method to draw a line tangent to two given circles

Tangent To Two Circles

Draftsman's method to draw a line tangent to two given circles