xli PREFACE. 



piece, " On the Estimation of Skill in Target- 

 Shooting," has for one of its objects the correction 

 of an error in one of the Author's former works, 

 while, at the same time, calling attention to a 

 subject generally, and even nationally, interest- 

 ing. 



COLLIXGWOOD, June 8, 1866. 



