imit 

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SCIENTIFIC SIDE-LIGHTS 



402 



scopist well knows the great advantage of 

 limiting his field of view when he is exam- 

 ining objects of the greatest difficulty. And 

 every one who has been accustomed to visit 

 picture-galleries is aware how much more 

 fully he is able to appreciate a picture when 

 he looks at it in such a manner that its sur- 

 roundings are kept out of his view. 



To be able to bring our fullest measure of 

 visual power to bear upon any object we de- 

 sire to examine, and at the same time to see 

 surrounding objects with sufficient distinct- 

 ness for the recognition of their local rela- 

 tion to it, is, thus, far more advantageous 

 to us than would be the extension of that 

 highest degree of visual power over the 

 whole range at once. Here again, therefore, 

 the asserted imperfection of the eye as an 

 optical instrument proves to be the very con- 

 trary, when its structure and action are re- 

 garded in their relations to the use we make 

 of the organ, added force being thus given to 

 the .final conclusion drawn by Professor 

 Helmholtz that " the adaptation of the eye 

 to its function is most complete, and is seen 

 in the very limits which are set in its de- 

 fects." Those who quote his previous state- 

 ment, for the purpose of depreciating the 

 perfection of the organ, are bound in hon- 

 esty to cite this also. CARPENTER Nature 

 and Man, lect. 15, p. 426. (A., 1889.) 



1961 . LIMITATION, LAW OF Abso- 

 lute Satisfaction Possible. We feel our own 

 ignorance and our own helplessness, not 

 because we have reached, but because we 

 cannot reach, the limits of our intellectual 

 powers, and because the desires which corre- 

 spond to them are consequently left unsatis- 

 fied. This is the difference between our- 

 selves and the lower animals. We can per- 

 fectly understand the absolute limitations 

 under which they lie, because in many of 

 our lower faculties we share these limita- 

 tions with the beasts. All their powers and 

 many of our own are exerted without any 

 sense of limitation, and this because of the 

 very fact that the limitation of them is 

 absolute and complete. In their own nature 

 they admit of no larger use. The field of 

 effort and of attainable enjoyment is, as re- 

 gards them, coextensive with the whole field 

 in view. Nothing is seen, or felt, or wished 

 for by them which may not be possessed. In 

 such possession all exertion ends and all 

 desire is satisfied. This is the law of every 

 faculty subject to a limit which is absolute; 

 and where this law does not apply, there we 

 may be sure that the limitation is not abso- 

 lute, but conditional. ARGYLL Unity of Na- 

 ture, ch. 4, p. 77. (Burt.) 



1962. LIMITATION OF IMPULSE 

 AND MOVEMENT Fatigue Diminished by 

 Habit. The first result of habit is that it 

 simplifies the movements required to achieve 

 a given result, makes them more accurate, 

 and diminishes fatigue. 



" The beginner at the piano not only 

 moves his finger up and down in order to 



depress the key, he moves the whole hand, 

 the forearm, and even the entire body, 

 especially moving its least rigid part, the 

 head, as if he would press down the key 

 with that organ too. Often a contraction of 

 the abdominal muscles occurs as well. Prin- 

 cipally, however, the impulse is determined 

 to the motion of the hand and of the single 

 finger. This is, in the first place, because 

 the movement of the finger is the movement 

 thought of, and, in the second place, because 

 its movement and that of the key are the 

 movements we try to perceive, along with 

 the results of the latter on the ear. The 

 more often the process is repeated, the more 

 easily the movement follows, on account of 

 the increase in permeability of the nerves 

 engaged. But the more easily the move- 

 ment occurs, the slighter is the stimulus 

 required to set it up; and the slighter the 

 stimulus is, the more its effect is confined 

 'to the fingers alone. Thus, an impulse 

 which originally spread its effects over the 

 whole body, or at least over many of its 

 movable parts, is gradually determined to a 

 single definite organ, in which it effects the 

 contraction of a few limited muscles. In 

 this change the thoughts and perceptions 

 which start the impulse acquire more and 

 more intimate causal relations with a par- 

 ticular group of motor nerves." SCHNEIDER 

 Der menschliche Wille, quoted by JAMES 

 in Psychology, vol. i, ch. 4, p. 112. (H. H. & 

 Co., 1899.) 



1963. LIMITS, FIXED, OF NATURAL 

 SCIENCE Ultimate Entities beyond Human 

 .Knowledge. Natural philosophy has a fixed 

 boundary that she is not permitted to step 

 across. It must be continually remembered 

 in spite of all discoveries that such things 

 as light, electricity, and magnetism cannot 

 be brought into experience because the 

 human intellect has nothing but a represen- 

 tation of things that possess materiality. 

 LIEBIG Thierchemie, p. 8. (Translated for 

 Scientific Side-Lights.) 



1964. LIMITS OF HUMAN KNOWL- 

 EDGE Chemistry Stops at Elements No Hu- 

 man Discovery Goes Beyond. When we at- 

 tempt to break up the various materials 

 around us into simpler parts we soon reach 

 a class of substances which cannot be further 

 decomposed. Simple inspection will show 

 that granite rock, for example, is a mixture 

 of three minerals, called feldspar, mica, and 

 quartz. We know, also, that feldspar con- 

 sists of alumina, potash, and silica; that 

 mica contains the same materials in differ- 

 ent proportions, and that quartz is silica 

 alone. Lastly, the chemists have discovered 

 that alumina is composed of aluminum and 

 oxygen, potash of potassium and oxygen, 

 and silica of silicon and oxygen. But here 

 Ave must stop; for when you ask us of what 

 these last-named materials are made we find 

 ourselves in the condition of the old phi- 

 losopher, who got on very well with his flat 

 earth, supporting it on an elephant, and the 



