364 ANNUAL OF SCIENTIFIC DISCOVERT. 



Lord Rosse adverted to the peculiar condition of equilibrium which 

 must, prevail in these systems, or rather to the forces which are required 

 to produce the peculiar constitution which they indicate, and pointed 

 out the difficulties of such an investigation. It could, however, not be 

 undertaken with advantage till we possess a much more extended col- 

 lection of data, to which he would contribute to the utmost of his 

 power. The drawings exhibited were based on measures carefully 

 taken with a bar-micrometer (the only one available in such cases,) 

 and he believed they might be trusted. He had already described 

 the improvement effected by supporting the speculum on its levers by 

 81 balls, and mentioned the striking fact, that with a speculum weigh- 

 ing 3^- tons, a slight pressure of the hand would deform for a time the 

 image of a star. 



ON THE MOTIONS OP NUMEROUS SMALL BODIES HOUND THE 

 SUN ; AND THE PHENOMENA RESULTING FROM THEM. 



THE following communication, on the above subject, was prepared 

 for the American Association, for the advancement of science, by 

 Daniel Yaughan, of Kentucky. 



It appears from recent discoveries that the sun numbers among his 

 attendants, not only planets, asteroids, and comets, but also immense 

 multitudes of meteoric stones and shooting stars. Great magnitude, 

 indeed, is not essential for membership in the Solar system, while, at 

 the same time, there is a necessary limit to the size of projectiles in 

 the same manner as there is to the size of edifices, in consequence 

 of the strength of bodies increasing in a slower proportion than their 

 weight, or the force required for their motion. The larger planets, 

 though formed of materials possessing many thousand times the 

 tenacity of iron, should be shattered to fragments in receiving their 

 present velocities, not only from an impulse, but from any force 

 applied under the most favorable circumstances. This should lead us 

 to conclude that all planetary motion, if it originated from natural 

 causes, must have been first imparted to a number of small masses 

 which subsequently united to form the larger members of the solar 

 system. 



If a rare medium be diffused through the planetary spaces, the 

 smallest attendants of the sun will be the most sensible to its influ- 

 ence ; as similar solids traversing it with the same velocity, must 

 sustain a loss of motion inversely proportional to their linear dimen- 

 sions. Supposing the medium at rest while our system is moving to 

 the constellation of Hercules, my investigations show, that a very 

 singular result will be produced on the orbits of the smallest mem- 

 bers of our system, when their diminutive size, or great rarity, causes 

 the resistance of the medium to predominate over the disturbances 

 proceeding from the action of the planets. The eccentricity of their 

 orbits must continually change, until they all describe very elongated 

 ellipses having the lower apsis directed to the constellation to which 

 the sun is advancing. The medium will also produce a motion of 



