Centres of gravity of pyramids, wedges and the tetrahedron

Centre of gravity of a pyramid between its third and fourth

Every pyramidal body whose sides meet in a point has the centre of its gravity between the third and the fourth part of its length, but toward the base. A wedge q has its centre of gravity at the third part of its length.

Tetrahedron: centre of gravity at the crossing of its axes

The centre of gravity of the body of four triangular bases lies at the intersection of its axes and stands at the fourth part of its length, illustrated by the tetrahedra with their axes drawn in.

Three centres within the pyramid at 1/2, 1/3 and 1/4 of its height

In this part of the pyramid the centres are of three various natures: one stands at half its height, another at the third, and the third centre at the fourth of that height.

Point a between the third and fourth of the axis

A lower-margin construction marks that a will fall between the third and the fourth of the axis of such a pyramid.

b exceeds d in figure a

A left-margin figure records the simple relation that b exceeds d in figure a.

A column unequal in thickness

One of the drawings at the lower right is captioned a column unequal in thickness, a tapering solid taken up in the same centre-of-gravity study.

Nella metà inferiore del foglio a destra figura con scritte:

Figure con lettere.

A lato delle figure:

Nel margine inferiore del foglio figura con lettere:

Nel margine sinistro figure con lettere:

Nella metà superiore del foglio:

In the lower half of the sheet, at the right, a figure with writing:

Figures with letters.

Beside the figures:

In the lower margin of the sheet, a figure with letters:

In the left margin, figures with letters:

In the upper half of the sheet: