POPULAR MISCELLANY. 



571 



bits to touch at the colliding point, the re- 

 sulting fragments would be-driven forth in 

 a plane perpendicular to the course of their 

 common center of gravity. If the velocity 

 from the impulse were thirty-two per cent, 

 of that required for describing a circle, they 

 would be constrained to move in ellipses 

 varying in eccentricity between *32 and 

 1024 ; and about seven eighths of the 

 known asteroids conform to this limitation 

 in the form of their orbits. Had the motion 

 of both planets been merely progressive and 

 coincident with the ecliptic, the orbital in- 

 clination for the fragmentary group would 

 vary from to about 19, yet the range 

 would pass many degrees beyond this lim- 

 it through the influence of rotation in the 

 great spheres in causing their matter to fly 

 more rapidly into space in a polar direction 

 in the early stage of the collision. Yet this 

 rotational movement would prevent the ec- 

 centricities of the numerous orbits from as- 

 suming the proportions which might be ex- 

 pected if the line of motion of the colliding 

 orbs did not pass through their centers as 

 in the supposed case. 



There is another clew to the cosmical 

 history of the region between Mars and 

 Jupiter. The orbits of Saturn's moons 

 show a near conformity to geometrical pro- 

 gression, and, taking the common rates at 

 \-Z0*15&, the following table gives the em- 

 pirical as compared with the actual distances 

 in equatorial semi-diameters of the primary : 



It appears from this table that two con- 

 secutive satellites are missing in each of the 

 chasms in the Saturnian family, and this 

 evidence of their transformation into aste- 

 roids seems more reasonable on considering 

 the disturbing influences of Titan and Ja- 

 petus on their planetary neighbors. The 

 array of the satellites near Saturn would 

 also lead to the belief of more worlds than 

 one near the sun, and the vain search for 



Vulcan would render more probable the 

 existence of an asteroidal group within the 

 orbit of Mercury. 



Listening to the Pnlse. We take from 

 the "Lancet" an account of a new instru- 

 ment the sphygmophone invented by Dr. 

 Richardson, of London, and which trans- 

 mutes the movements of the arterial pulse 

 into loud telephonic sounds. The needle 

 of a Pond's sphygmograph is made to trav- 

 erse a metal or carbon plate, which is con- 

 nected with the zinc pole of a Leclanche cell. 

 To the metal stem of the sphygmograph is 

 then attached one terminal of a telephone, 

 the other terminal being connected with the 

 opposite pole of the battery. When the 

 whole is ready the sphygmograph is brought 

 into use as if a tracing were about to be 

 taken, and when the pulsation of the needle 

 from the pulse-strokes is secured, the needle, 

 which previously was held back, is thrown 

 over, so as to make its point just touch the 

 metal or carbon plate, and to traverse the 

 plate to and fro with each pulsation. In 

 so moving, three sounds, one long and two 

 short, are given out from the telephone, 

 which sounds correspond with the first, sec- 

 ond, and third events of sphygmographic 

 reading. In fact, the pulse talks telepho- 

 nically, and so loudly, that when two cells 

 are used the sounds can be heard by a large 

 audience. 



The Audiometer. " Audimeter," or 

 "audiometer," is the name given to an in- 

 strument invented by Professor Hughes, 

 with the aid of which a person's power of 

 hearing sounds can be very accurately mea- 

 sured. It is formed of a small battery of 

 one or two Leclanche cells, a new micro- 

 phonic key, two fixed primary coils, a grad- 

 uated insulated bar, to which at each end 

 one of the fixed coils is attached, a second- 

 ary induction coil, which moves along the 

 graduated bar, and a telephone, the termi- 

 nals of which are connected with the termi- 

 nals of the induction coil. The principle 

 of the audiometer is based on the physical 

 fact that when the battery is in action, and 

 a current is passing through the two pri- 

 mary coils, the secondary coil on the bar 

 becomes charged by induction whenever it 

 is brought near to either of the primary 

 coils ; but, when it is brought to the precise 



