bosom-board

Use for ironing shirts a bosom-board, made of seasoned wood a foot wide, one and a half long, and an inch thick; cover it well by tacking over very tight two or three folds of flannel, according to the thickness of the flannel.

Practical Suggestions for Mother and Housewife Marion Mills Miller 1906

It is a plain, old-fashioned wooden chair, with a kind of bosom-board on the right arm, upon which Jefferson used to rest his Declaration of Independence whenever he wanted to write it.

The Wit and Humor of America, Volume IX (of X) Various 1887

A bosom-board, on which to iron shirt-bosoms, should be made, one foot and a half long, and nine inches wide, and covered with white flannel.

A Treatise on Domestic Economy For the Use of Young Ladies at Home and at School Catharine Esther Beecher 1839