427 



SCIENTIFIC SIDE-LIGHTS 



Mariner's 

 Materialism 



in Their Mildest Moods. At the first re- 

 corded eruption of Vesuvius the elder Pliny 

 lost his life in an attempt to approach the 

 mountain and examine the action which was 

 taking place there; and during the last 

 great outburst of the same volcano a band 

 of Neapolitan students, whose curiosity was 

 greater than their prudence, shared the 

 same fate. 



But in both these cases the inquirers paid 

 the penalty of having adopted a wrong 

 method. If we wish to examine the mode 

 of working of a complicated steam-engine, it 

 will be of little avail for us to watch the 

 machinery when the full blast of steam is 

 turned on, and the rapid movements of lev- 

 ers, pinions, and slides baffle all attempts 

 to follow them, and render hopeless every 

 effort to trace their connection with one 

 another. But if some friendly hand turn 

 off the greater part of the steam- supply, 

 then, as the rods move slowly backwards 

 and forwards, as the wheels make their 

 measured revolutions, and the valves are 

 seen gradually opening and shutting, we 

 may have an opportunity of determining the 

 relations of the several parts of the machine 

 to one another, and of arriving at just con- 

 clusions concerning the plan on which it is 

 constructed. JUDD Volcanoes, ch. 2, p. 7. 

 (A., 1899.) 



2091. MARVELOUS, THE, TRANS- 

 FORMED Newton's Discovery of the Laws 

 of the Cometary Motions. In order to upset 

 the theory of prodigies it was necessary to 

 find the laws of the motion of comets. This 

 is what Newton did in the case of the comet 

 of 1680. Having ascertained that, according 

 to the laws of universal gravitation, the 

 path of the comet should be a very elonga- 

 ted curve, he attempted, assisted by Halley, 

 his coadjutor and friend, to represent math- 

 ematically the course of the new body, and 

 completely succeeded. Halley energetically 

 took up this branch of astronomy, and find- 

 ing later on that the comet of 1682 was 

 similar in its path round the sun to two 

 comets previously observed, in 1531 and 

 1607, recognized it as undoubtedly the same 

 comet, which should, therefore, reappear 

 about 1758. 



By the theoretical labors of Newton and 

 by the calculations of Halley the prediction 

 of Seneca was fulfilled; comets, or at least 

 some of them, follow regular orbits. Their 

 return could be foreseen; they ceased to be 

 accidental apparitions; they were true 

 celestial bodies with a fixed and regular 

 course. The marvelous disappeared, or, 

 to speak more correctly, it was transformed. 

 FLAMMARION Popular Astronomy., bk. v, 

 ch. 1, p. 485. (A.) 



2092. MASS ENVELOPING HERCU- 

 LANEUM AND POMPEII Rivera of Mud 

 or Alluvium Aqueous Lava. In addition 

 to the ejections which fall on the cone, and 

 that much greater mass which finds its way 

 gradually to the neighboring sea, there is a 

 third portion, often of no inconsiderable 



thickness, composed of alluviums, spread 

 over the valleys and plains at small dis- 

 tances from the volcano. Aqueous vapors 

 are evolved copiously from volcanic craters 

 during eruptions, and often for a long time 

 subsequently to the discharge of scoriae and 

 lava : these vapors are condensed in the cold 

 atmosphere surrounding the high volcanic 

 peak, and heavy rains are thus caused. The 

 floods thus occasioned sweep along the im- 

 palpable dust and light scori* till a current 

 of mud is produced, which is called in Cam- 

 pania " lava d' acqua," and is often more 

 dreaded than an igneous stream (lava di 

 fuoco ) , from the greater velocity with which 

 it moves. So late as the 27th of October, 

 1822, one of these alluviums descended the 

 cone of Vesuvius, and, after overspreading 

 much cultivated soil, flowed suddenly into 

 the villages of St. Sebastian and Massa, 

 where, filling the streets and interior of 

 some of the houses, it suffocated seven per- 

 sons. It will, therefore, happen very fre- 

 quently that, towards the base of a volcanic 

 cone, alternations will be found of lava, 

 alluvium, and showers of ashes. LYELL 

 Principles of Geology, bk. ii, ch. 24, p. 385. 

 (A., 1854.) 



2093. MASTERY, PROGRESSIVE, OF 

 BODY BY MIND The combined use of 

 anesthetics and antiseptics has almost 

 robbed the surgeon's knife of its terrors, and 

 has enabled the most deeply seated organs 

 to be laid open and operated upon with suc- 

 cess. As a result, more lives are probably 



'now saved by surgery than by any other 

 branch of medicine. WALLACE The Wonder- 

 ful Century, ch. 14, p. 149. (D, M. & Co., 

 1899.) 



2094. MATERIALISM AND IDEAL- 

 ISM Contrasted Claims Possible Reconcilia- 

 tion. But when the materialists stray be- 

 yond the borders of their path and begin to 

 talk about there being nothing else in the 

 universe but matter and force and necessary 

 laws, I decline to follow them. I go back 

 to the point from which we started, and to 

 the other path of Descartes. I remind you 

 that we have already seen clearly and dis- 

 tinctly, and in a manner which admits of no 

 doubt, that all our knowledge is a knowledge 

 of states of consciousness. " Matter " and 

 " force " are, so far as we can know, mere 

 names for certain forms of consciousness. 

 " Necessary " means that of which we can- 

 not conceive the contrary. " Law " means 

 a rule which we have always found to hold 

 good, and which we expect always will hold 

 good. Thus it is an indisputable truth that 

 what we call the material world is only 

 known to us under the forms of the ideal 

 world; and, as Descartes tells us, our 

 knowledge of the soul is more intimate and 

 certain than our knowledge of the body. If 

 I say that impenetrability is a property of 

 matter, all that I can really mean is that 

 the consciousness I call extension and the 

 consciousness I call resistance constantly 

 accompany one another. Why and how they 



