ON DEFLECTIVE FORCES. 41 



purposes of gunnery, an estimation governed by experience is found to be 

 the best guide; at the same time there is no doubt but that some assistance 

 may be obtained from theory and from experiment. Those who are desirous 

 of pursuing the subject, may find much information relating to it, collected by 

 Professor Robison, in the article Projectile of the Encyclopaedia Britannica. 



VOL. I. 



