Abstract
According to a study conducted by the Institute for the Science of Labor in 1943，a professional carpenter uses 179 different tools on average. Among them are 49 types of chisels belonging to 12 separate categories. This constitutes the standard set of chisels used in modern carpentry.
What types of chisels were used from the 17th to 19th centuries? My research into various reference materials concerning architectural chisels has yielded the following findings.
(1) Architectural chisels can be classified into three categories; (a) those for treating conjoined parts; (b) those for boring holes for connecting devices such as wooden pegs and nails; and (c) those for boring curved holes. At least about 50 chisels， in 14 different varieties， have been used by trained professional carpenters in the 17th-–19th century.
(2) Architectural chisels that share a standard shape have been given different names acoording to blade width.
(3) The average length for standard –shape architectural chisels can be estimated at about 1 “shaku” ， of about 300 millimeters.
(4) The handles of architectural chisels are made of oak， ebony， rosewood and hinoki， or Japanese cypress.
(5) The blades of architectural chisel have a standard width. The difference between the narrowest and widest blades was about 1 millimeter. I could not confirm a similar standard for neck length.
(6) Architectural chisels are made by inserting the tang into the handle， and then reinforcing the connection with the ferrule.
(7) Changes in working postures resulting in improved work efficiency seem to have occurred sometime from the late 18th to early 19th century.
(8) Among the 29 architectural chisels used by a single carpenter in the early 19th century， seven different signatures inscribed by blacksmiths have been identified.
