40 



ON THE GENERAL DIFFUSION OF KNOWLEDGE. 



lines for determining the perpendicular elevation 

 of iM phenomenon. In reference to luminous 

 meteors, as they are most frequently seen in The 

 night-time, men of science and persons of ele 

 vated rank have seldom opportunities of observ 

 ing their diversified phenomena, and the circum 

 stances with which they are preceded and ac 

 companied. But while persons of this class 

 are reclining on beds of down, or regaling them 

 selves at the festive board, hemmed in from the 

 view of the surrounding skv by the walls and 

 curtains of their splendid apartments, many in 

 the lower walks of life are &quot;keeping watch by 

 night,&quot; or travelling from place to place, who 

 have thus an opportunity of observing every 

 variety of atmospherical phenomena ; and it is 

 not unlikely may have seen several species of 

 luminous and fiery meteors unknown to the sci 

 entific world. Were persons of this descrip 

 tion, particularly watchmen, soldiers, sailors, 

 mail-coach guards, policemen, and such like, 

 capable of observing such appearances with 

 scientific interest and accuracy, and of record 

 ing their observations, various important addi 

 tions might be made to the facts which compose 

 the natural history of the atmosphere. 



Similar additions mi&amp;lt;jht be made to our know 

 ledge of thunder-storms, were their phenomena 

 and concomitant circumstances accurately noted 

 by a vast, number of persons in different places. 

 ft mijht, for example, be determined, from a 

 multitude of observations made with this special 

 object in view, at what distance from the earth 

 a thunder-cloud may explode without danger? 

 in what circumstances, and at what elevation 

 it generally attains its striking distance, and 

 brings us within the range of its destructive in 

 fluence ? what particular effects, hitherto un 

 observed, are produced by lightning on animal, 

 vegetable, and mineral substances? to what 

 practical purposes its agency might be applied, 

 and how its destructive ravages might be 

 averted or diminished ? The same remarks 

 will apply to the singular phenomenon of mete 

 oric stones. These have seldom been observed 

 at the instant of their descent by men addicted 

 to philosophical research ; but chiefly by pea 

 sants, labourers, and mechanics, who, at pre 

 sent, are generally unqualified for attending to 

 every circumstance in the preceding and conco 

 mitant phenomena connected with their descent, 

 with the discerning eye of a philosopher ; and 

 therefore, we may still be ignorant of certain 

 important facts in the history of the fall of these 

 bodies, which may long prevent us from form 

 ing any rational theory to explain their causes, 

 or to determine the regions whence their origin 

 is derived. 



Astronomy. My next illustration shall be 

 taken from the science of astronomy. Though 

 this is among the oldest of he sciences, and its 

 general principles are established with greater 



precision than those of almost any other depart- 

 ment of science, yet many dcsiderat.a requisite 

 to its perfection, still remain to be ascertained. 

 The late discovery of several new planets, both 

 primary and secondary, leads us to conclude, 

 that other globes of a similar nature, belonging 

 to our system, may still lie hid in the* distant 

 spaces of the firmament. The spheroidal figure 

 of some of the planets their periods of rota 

 tion the nature of the changes which appear to 

 take place on their surfaces or in their atmos 

 pheres the precise nature of the solar spots, 

 the causes of their changes, and the influence 

 which those changes produce on our earth or at 

 mosphere the parallax of the fixed stars the 

 rate of motion of the planetary system in abso 

 lute space the gradual formation of nebuise 

 the nature of variable stars the number of co 

 mets, their periods, the nature of their tails and 

 atmospheres, and their uses in the system of 

 nature with many other interesting particulars 

 of a similar description, still remain to be ascer 

 tained. To determine such objects, requires a 

 multiplicity of long-continued observations in 

 every region of the heavens ; and it must be 

 evident, that the more we increase the number 

 of astronomical observers, the greater chance 

 we shall have of acquiring a more accurate and 

 comprehensive knowledge of the bodies which 

 roll in the distant regions of the universe, and 

 of the relations they bear to one another, and to 

 the whole system of nature. 



This position might be illustrated by a few 

 examples. The surface of Jupiter has been 

 found to be diversified with a variety of spots 

 and belts : the belts, which are considerably 

 darker than the general surface of the planet, 

 are observed to vary in their number, distance, 

 and position. Sometimes only one or two, and 

 sometimes seven or eight belts have been ob 

 served ; sometimes they are quite distinct, and 

 at other times they seem to run into each other ; 

 and, in some instances, the whole surface of this 

 planet has appeared to be covered with small 

 curved belts that were not continuous across his 

 disk. 



The following figures represent some of the 

 diversified views which Jupiter sometimes ex* 

 hibits. 



Fig. 1, is copied from Dr. Long, and appears 

 to be one of the views of this planet taken Ly 

 the celebrated Cassini. It consists of about 

 nine different belts. Fig. 2, is copied from 

 Schroeter, and exhibits a view of Jupiter about 

 the time of its occultation by the moon, on the 

 7th of April 1792. Fig. 3, is one of Sir W. 

 Herschel s views of this planet, as it appeared 

 on the 28th May 1780, when the whole disk of 

 Jupiter appeared covered with small curved 

 belts, or rather lines, that were not continuous 

 across his disk. Fig. 4, contains a view which 

 is nt-arly the appearance which Juf.r exhioits 



