Found these in an old book (online):
VOL II The stone age in North America; an archæological encyclopedia of the implements, ornaments, weapons, utensils, etc., of the prehistoric tribes of North America (1910) Author: Moorehead, Warren King, 1866-1939
![](http://i246.photobucket.com/albums/gg112/jackcrafty/ScreenShot2013-06-01at20049PM_zps9f21a9f8.png)
There's no scale but in another book I have (The Archaeology of New York State - Revised Edition, William A. Ritchie, 1980) the average length of similar slate points is 3".