691 



SCIENTIFIC SIDE-LIGHTS 



will certainly not die out, and to the latter 

 the majority will always belong. HELM- 

 HOLTZ Popular Lectures, lect. 5, p. 224. ( L. 

 G. & Co., 1898.) 



3416. THICKNESS OF EARTH'S 

 CRUST Theories Corrected by Advancing Sci- 

 ence. The earth is known gradually to aug- 

 ment in temperature as we pierce it deeper, 

 and the depth has been calculated at which 

 all known terrestrial bodies would be in a 

 state of fusion. Owing, however, to the 

 enormous pressure of the superincumbent 

 layers, the deeper strata, according to Mr. 

 Hopkins, would require a far higher tem- 

 perature to fuse them than would suffice to 

 fuse the strata near the earth's surface. 

 Hence he inferred that the solid crust must 

 have a considerably greater thickness than 

 that given by a calculation which assumes 

 the fusing points of the superficial and the 

 deeper strata to be the same. Mr. Hopkins, 

 therefore, rejected the estimate of geologists 

 that the earth could be a molten nucleus 

 covered by a crust only 100 miles in thick- 

 ness, concluding that the depth of the crust 

 must be at least 800 miles. Sir William 

 Thomson considers it " extremely improbable 

 that any crust thinner than 2,000 or 2,500 

 miles could maintain its figure with suffi- 

 cient rigidity against the tide-generating 

 forces of sun and moon, to allow the phe- 

 nomena of the ocean tides and of precession 

 and nutation to be as they now are." 

 TYNDALL Heat a Mode of Motion, lect. 6, p. 

 148. (A., 1900.) 



3417. "THING IN ITSELF " The 



Unconditioned Unthinkable, and also In- 

 credible. In metaphysics the assertion that 

 we can never attain to any knowledge of 

 things " in themselves " does not mean sim- 

 ply that we know things only in a few re- 

 lations out of many. It does not mean 

 even that there may be and probably are a 

 great many relations which we have not 

 faculties enabling us to conceive. All this 

 is quite true, and a most important truth. 

 But the metaphysical distinction is quite 

 different. It affirms that if we knew things 

 in every one of the relations that affect 

 them, we should still be no nearer than be- 

 fore to a knowledge of " things in them- 

 selves." . . . 



Now, as the very idea of knowledge con- 

 sists in the perception of relations, this af- 

 firmation is, in the purest sense of the word, 

 nonsense that is to say, it is a series of 

 words which have either no meaning at all 

 or a meaning which is self-contradictory. It 

 belongs to the class of propositions which 

 throw just discredit on metaphysics mere 

 verbal propositions, pretending to deal with 

 conceptions which are no conceptions at all, 

 but empty sounds. The "unconditioned," 

 we are told, " is unthinkable " ; but words 

 which are unthinkable had better be also un- 

 speakable, or at least unspoken. It is alto- 

 gether untrue that we are compelled to be- 

 lieve in the existence of anything which is 



" unconditioned " in matter with no quali- 

 ties in minds with no character in a God 

 with no attributes. Even the metaphysi- 

 cians who dwell on this distinction between 

 the relative and the unconditioned admit 

 that it is one to which no idea can be at- 

 tached. Yet, in spite of this admission, they 

 proceed to found many inferences upon it, 

 as if it had an intelligible meaning. AR- 

 GYLL Unity of Nature, ch. 4, p. 90. (Burt.) 



3418. THIRST OF ALPINE CLIMBER 



Milk a Perfect Refreshment. During the 

 previous night I had been very unwell, and 

 as I climbed the slope I suffered from in- 

 tense thirst. Water seemed powerless to 

 quench the desire for drink. We reached 

 a chalet, and at our request a smart young 

 Senner caught up a pail and soon returned 

 with it full of delicious milk. The effect of 

 the milk was astonishing. It seemed to lu- 

 bricate every atom of my body, and to ex- 

 hilarate with its fragrance my brain. TYN- 

 DALL Hours of Exercise in the Alps, ch. 9, 

 p. 92. (A., 1898.) 



3419. Snow and Ice In- 

 crease Distress. We had plodded on for 

 hours soddened by the solar heat and 

 parched with thirst. There was 



Water, water everywhere, 



But not a drop to drink : 



for, when placed in the mouth, the lique- 

 faction of the ice was so slow, and the loss 

 of heat from the surrounding tissues so 

 painful, that sucking it was worse than 

 total abstinence. In the midst of this solid 

 water you might die of thirst. TYNDALL 

 Hours of Exercise in the Alps, ch. 15, p. 170. 

 (A., 1898.) 



342O. THOUGHT AND FEELING 

 HAVE NO EXTENSION Intense Pleasure 

 or Pain Annuls Space and Time. When 1 

 am studying a brain and nerve-communica- 

 tions, I am engrossed with properties ex- 

 clusively belonging to the object or material 

 world. I am unable at that moment (except 

 by very rapid transitions or alternations) 

 to conceive a truly mental fact, my truly 

 mental consciousness. Our mental experi- 

 ence, our feelings and thoughts, have no ex- 

 tension, no place, no form or outline, no 

 mechanical division of parts ; and we are 

 incapable of attending to anything mental 

 until we shut off the view of all that. Walk- 

 ing in the country in spring, our mind is 

 occupied with the foliage, the bloom, and 

 the grassy meads all purely objective 

 things: we are suddenly and strongly ar- 

 rested by the odor of the May blossom ; we 

 give way for a moment to the sensation of 

 sweetness; for that moment the objective 

 regards cease; we think of nothing extend- 

 ed; we are in a state where extension has 

 no footing; there is, to us, place no longer. 

 Such states are of short duration, mere fits, 

 glimpses ; they are constantly shifted and al- 

 ternated with object states, but while they 

 last and have their full power we are in 

 a different world; the material world is blot- 



