414 Intelligence and Miscellaneous Articles. 



will be read only with surprise. I can here intimate only that Gruit- 

 huisen proposes, partly, to sink perpendicular shafts of several 

 thousand feet depth, and partly to drive horizontal galleries in the 

 direction of a chord (under the Alps ! to a length of 15 miles) through 

 the ground, and, together with practical locomotive purposes, to 

 apply them to physical-astronomical investigations. L. c. p. 21, we 

 read, " But it is moreover incalculable ivhat the astronomer in such 

 a tunnel, provided with a shaft as dry as possible, for observations 

 deserving attention, could accomplish. Common people would set 

 up a terrible roar of laughter, if told that, under the mountains, 

 at such depths an excellent observatory could be built, in which to 

 make observations of a peculiar sort, which would furnish us with 

 data in the highest degree desirable and to be expected, and a quan- 

 tity of useful data at present unknown, which must supply to both 

 practical and theoretical astronomy new aids for still greater geo- 

 metrical accuracy and a great number of new results. To this sub- 

 terranean observatory I will give the name of catachthonic observa- 

 tory or catachthonium." Now I believe that at the time when the 

 above was printed others besides merely common people would have 

 set up a terrible roar of laughter, if they had seen Grruithuisen's 

 dissertation. 



The chief instruments of the catachthonium were, according to 

 Grruithuisen, of two kinds : — first, large, accurately turned rings at 

 the mouths of the shafts, in order on them as on ring micrometers, 

 from a distance of from 100 to 2000 feet, to observe the transits of 

 the stars by day also (in consequence of the presumed visibility of 

 the stars from deep pits), and (p. 22) "to obtain immediately clear 

 geocentric observations perfectly free from refraction? On this it says, 

 at p. 28, " What even these few instruments could accomplish and 

 settle in relation to the proper motions of many fixed stars, the sol- 

 stice, precession, nutation, aberration, the course of the moon, and the 

 like, may be expected to be so much the more, as the position of the 

 most simple instruments must be the most invariable possible, because 

 here the variations of the temperature are almost =0; so that the 

 necessary clocks do not require even a compensation-pendulum ; and, 

 besides, there is absolutely nothing present which could be sub- 

 ject to so much as a slight variation of temperature; wherefore 

 the place of such an observatory cannot be supplied by any observa- 

 tory above ground, however efficient." Here we have Lamont and 

 Carrington's subterranean observatories anticipated a generation 

 previously. 



The second principal instrument of the catachthonium was to 

 consist of fine plummets suspended on wires from 150 to 1500 feet 

 in length, in order thereon (according to p. 32) to make "observable 

 the motion of the earth in its orbit," " and perhaps even the difference 

 in the annual velocity of this motion." Namely, at pp. 30 and 31 it 

 is shown that, during each rotation of the earth, the rotational ve- 

 locity of a point in the equator is once added to the orbital velocity, 

 and once subtracted from it, and thereby are produced variations in 

 the horizontal component of the earth's gravitation, which depend 



