In 1777, Samuel Miller invented the circular sawin England, the round metal disk type of saw that cuts by spinning and is used hand-held or table-mounted. Large circular saws are found in saw mills and are used to produce lumber. In 1813, Shaker-Sister, Tabitha Babbitt (1784-1854) invented the first circular saw used in a saw mill. Babbitt was working in the spinning house at the Harvard Shaker community in Massachusetts, when she decided to invent an improvement to the two-man pit saws that were being used for lumber production. Tabitha Babbitt is also credited with inventing an improved version of cut nails, a new method of making false teeth, and an improved spinning wheel head.
5-3/8 inch blade
Reciprocating saw
from Wikipedia
A reciprocating saw is a type of saw in which the cutting action is achieved through a push and pull reciprocating motion of the blade.
The term reciprocating saw is commonly assigned to a type of saw used in construction and demolition work. This type of saw, also known as a recipro saw, Sabre Saw, or Sawzall (a trademark of the Milwaukee Electric Tool Company) has a large blade resembling that of a jigsaw and a handle oriented to allow the saw to be used comfortably on vertical surfaces. The typical style of this saw has a foot at the base of the blade, also similar to a jigsaw. The user rests this foot against the surface being cut so that the tendency of the blade to push away from or pull towards the cut as the blade travels through its cycle can be countered.
www.ddhw.org---
Olive Oil 
顶顶大腕卧底
