1 74 Mr. Bell on the motions of the eye, &c. 
oblique to the line of motion, than if it lay in the line on which 
the body moves. If the oblique muscles were either oppo- 
nents or coadjutors of the recti, there appears no reason why 
they should be oblique, but the contrary ; for as the points of 
their insertion must move more rapidly than those of the 
recti, they are unsuitable. On the other hand, that there may 
be no difference in the time of the action and relaxation of 
the several classes, we see a reason why one rectus should be 
opposed by another, and why there being occasion for one 
oblique, its antagonist should also be oblique. 
In proportion as a muscle gains velocity by its obliquity, it 
loses power ; from the obliquity, therefore, of these muscles 
believed to be opposed to the recti, and from their being two 
of them to four of the latter, they are disproportioned in 
strength, and the disproportion proves that the two classes of 
muscles are not antagonists. 
By dissection and experiment it can be proved, that the 
oblique muscles are antagonists to each other, and that they 
roll the eye in opposite directions, the superior oblique direct- 
ing the pupil downwards and outwards, and the inferior ob- 
lique directing it upwards and inwards. But it is proved that 
any two of the recti muscles are equal to the direction of the 
pupil in the diagonal between them, and there is no reason 
why an additional muscle should be given, to direct the pupil 
upwards and inwards more than upwards and outwards, or 
downwards and inwards. It is evident then, that the oblique 
muscles are not for assisting the recti in directing the eye to 
objects, but that they must have some other appropriate office. 
If we proceed farther, it must be by experiment. 
