. An essay on the nature and the consequences of anomalies of refraction . condition. V AND A AS MODIFIED BY AGE. 53 Figure 11 illustrates the directions that areassumed in a high-grade, temporarily progres-sive M. Figure 12 shows the course that is found ina very high, permanently progressive degree, LXXXII. From this, it can be seen that it is T 235 JL15 ii 1T^ 2 ^T 1 ■5 1 M. /O 15 20 Z5 30 S5 40 4S 50 55 60 65 70 75 80 -^ \ \ \ s \ N, \ v. ^ -^ ^ r V / T^ Fig. II. an error to suppose that M, as a rule, lessenswith an increase of years. The cause of thisincorrect opinion is twofold. In the f
. An essay on the nature and the consequences of anomalies of refraction . condition. V AND A AS MODIFIED BY AGE. 53 Figure 11 illustrates the directions that areassumed in a high-grade, temporarily progres-sive M. Figure 12 shows the course that is found ina very high, permanently progressive degree, LXXXII. From this, it can be seen that it is T 235 JL15 ii 1T^ 2 ^T 1 ■5 1 M. /O 15 20 Z5 30 S5 40 4S 50 55 60 65 70 75 80 -^ \ \ \ s \ N, \ v. ^ -^ ^ r V / T^ Fig. II. an error to suppose that M, as a rule, lessenswith an increase of years. The cause of thisincorrect opinion is twofold. In the first place,p actually recedes from the eye, and this whichwas considered as a lessening of M, would onlytake place if r were to withdraw from the , the pupil grows smaller, and conse- 54 ANOMALIES OF REFRACTION. quently, on account of smaller circles of diffu-sion, the subject can often see better at a dis-tance during advanced age, in spite of a slightlyincreased M. LXXXIII. Pr is not excluded by minor grades /O /S 20 2S 30 35 40 45 SO 55 60 65 70 7S SO. Fig. 12. of M. It is said to be in existence the momentthat P is > 22 cm. In cases in which M = with A = diopters strength,^ issituated at thirty-three centimeters so thatPr = 4,5 diopters — 3 diopters = diopters. LXXXIV, The accompanying diagram (fig- V AND A AS MODIFIED BY AGE. 55 lire 13) exhibits approximately the course thataccommodation, as an attribute of age takes inH. The dotted Hne r^ r\ gives the progress ofthe total H, while r,„ r,„ illustrates that of themanifest. It is apparent that H, which is entirely latentat the outset, becomes increasingly manifest Meter /O /5 20 25 30 35 40 45 50 55 60 65 70 75 80 /{ [9 < \ s \ \ ^ N N s N V Tm. ^ \ ?, ^ ^ ^ Fig. 13. until by reason of increasing H, it is finally ren-dered wholly manifest. LXXXV. Numerous observations have madeit probable that eyes which towards the age offull growth have become emmetr
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