O'SHEA — A8PKCT8 OF MENTAL ECONOMY. 179 



unanimous in their praise of the softer variety. "They are so 

 much pleasanter to use" was the general testimony. I have ex- 

 amined most of the pencils of American manufacturers, I be- 

 lieve, and have found the Eagle Draughting to be the most satis- 

 f actorv. Our students are not so wise in their choice of pencils 

 as of pens. About seventeen per cent of those reporting use 

 hard pencils, while thirty-two per cent, use a medium quality. 

 The engineers use a hard pencil almost altogether, and this is 

 doubtless necessitated by the character of their work. 



Needless muscular stimulations wherever they occur must be 

 regarded as dissipating vital forces. Thievery of the most seri- 

 ous kind is constantly taking place. This is especially signifi- 

 cant in respect of the eyes. One who has reflected upon it can 

 not but be impressed with the marvellous delicacy required in 

 the proper control of the visual organs. During waking life 

 they are incessantly changing position so as to bring objects 

 within the range of vision. In order to accomplish this they 

 must be equipped with ocular muscles 1 so arranged as to secure 

 movements in all directions within a given orbit. 2 In the nor- 

 mal eye these muscles are exactly balanced in their pulling ca- 

 pacities and are never active except when the interests of vision 

 require action. But now it happens in frequent instances, so 

 frequent as to be alarming in these last few years when investi- 

 gations have been made so extensively, that one of the muscles 

 moving an eye may be more energetic than its fellows. Or 

 through some error in the functioning of the reflex nervous 

 mechanism it may be active when it ought to be at rest. It tends 

 then to pull the eye out of focus, which would render vision dou- 

 ble if it had its way ; but the will seeks to avert this calamity 

 and so must stimulate a muscle opposed to the overacting one 

 so as to neutralize its effect. This results then in incessant mus- 

 cular strain which is a source of constant waste of vital forces. 



Again, in the normal eye the lens and eye-ball are so con- 

 .structed that the focus falls exactly upon the retina. But now 



lf The four recti and the two oblique muscles. 



= See Le Conte, Sight, Chapters 2 and 3, for a good discussion of the muscular 

 mechanism of the eye and the philosophy of defects. See also Cohn, Hygiene of 

 the Eye, Chapters 1-8. 



