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LITERARY AND SCIENTIFIC. 



MECHANICS' INSTITUTION, BIRMINGHAM. 



Mr. Wallace commenced his third Lecture at this Institution, " On the Mental 

 Faculties of Man," by passing a ray of light through a glass cube filled with water. 

 The light was directed at an angle of about twenty-seven degrees, with a perpen- 

 dicular falling upon the centre of the bottom plate of the cube, at which point a wafer 

 was placed, that intercepted the light when the cube was empty. After entering the 

 medium tlirough a hole in a board, placed upon the upper surface, it was found to 

 proceed in a vertical direction, and, by the action of the upper and under surfaces, 

 to be suspended in the central plane. From this plane, when the eye was directed 

 underneath, it was clearly seen to issue ; thus shewing that light is not bent, or re- 

 fracted, in one continued line through any transparent medium, but that its direction 

 is solely influenced by the nature of the surfaces employed. To this peculiar modi- 

 fication in the operation of light, the lecturer referred all those phenomena which are 

 witnessed in the Polar and Torrid regions, and sometimes in more temperate 

 climates ; such as the appearance of objects above the horizon, when they are really 

 beneath it ; the multiplication and inversion of the images of objects ; and the 

 distortion of these images, either by elongation or contraction. To this peculiar 

 modification was also referred the nature of our sensations within the eye, which, of 

 necessity afforded us perceptions derived in all cases from the images of objects sus- 

 pended within the various mediums communicating them, and not from the objects 

 themselves. The next subject alluded to was the origin of our conceptions of num- 

 ber, proportion, and magnitude, illustrated by drawings; and of relation and com- 

 parison, as derived from the peculiar conformation of the eye itself; out of all which 

 the principles of perspective were stated to arise, and from which it was intimated 

 that we had derived the sciences of arithmetic, geometry, and trigonometry. The 

 various scales made use of for measuring palpable distances, in order to correct and 

 assist the eye, were then alluded to, and explained to be necessary, in consequence of 

 the physical properties of transparent bodies, which cause the images of objects to be 

 presented at apparent, instead of at real distances, in every instance. 



The fourth, and concluding lecture, treated of man in reference to the material 

 world. In the course of the lecture, man was considered as a recent inhabitant of 

 this planet ; and the particular localities which he had inhabited — as they are 

 described in ancient history — were stated to be still open to the inspection of the 

 traveller, with very few exceptions. At the same time, it was maintained that the 

 crust of the earth bore evident marks of distinct epochs, having long intervals of time 

 between them — the various strata containing organic remains peculiar to each ; but 

 that the ruins of the abodes of mankind were visible only upon the exterior part of 

 this crust ; and that no true organic remains of the human race had ever been dis- 

 covered within it. The diminution of the major axis of the elUpse described by the 

 orbits of comets, was alluded to as an argument that these bodies were incipient 

 worlds, similar to what the earth bore evident marks of having originally been ; as 

 was stated to be manifest from an examination of the various regular strata of which 

 its crust is composed. The deposition of these various strata were considered as the 

 result of animal architecture, and the assimilating powers of organized bodies ; and 

 a conclusion was drawn that inorganic matter was the result of these various opera- 

 tions, aided by subsequent crystallization, fermentation, or (its consequence) fusion 

 by volcanic agency. The position which man holds in the scale of creation was 

 inferred from all these considerations ; and the gift of speech — which he only enjoys — 

 was viewed as a means imparted to him of arriving at a comparatively perfect 

 knowledge of the constitution of matter, by the aid of reason and future inquiry. 



July, 1835. — VOL. ii. no. xii. 3 m 



