20 
REPORT—1854. 
and, taking water as I ’0, the following table shows the relative densities of ittml 
of the planetary bodies, following the order of their distances from the sun: .M 
cury, 15*7 ; Venus, 5‘9 ; Earth, 5*6; Mars, 5'2; Aerolites, 3*0; Asteroids 
Jupiter, 1*4. Another circumstance relating to aerolites which was alluded to bt 
Mr. Greg, was the periodicity of those bodies, and he mentioned more particularly i: 
19th of May, 29th of November, 13th of December, 15th to 19th of February, i&i 
26th of July, as being aeroliUc epochs, aerolite falls having been recorded on the f«* 
lowing days February 3. 10, 10,13, 15, 15, 15, 18, 18, 18,19,19,25, 27,2:; M- 
9. 10, 17, 17.17.18, 19, 19. 20, 22, 26,26,27,28; July 3, 3,4.7, 8,12,14,!M*. 
22 , 24, 24, 26, 26, 26, 30 ; November 5, 7. 11, 13, 17, 20 , 23, 25,27, *9, ».«?•« 
30, 30; December 11, 13, 13, 13, 13, 13, 11, 25, 28. In referring, however, u< 
epochs most remarkable for the periodical displays of luminous meteors, a* 5 
ber and August 9lh to 14th days, Mr. Greg observed that the number of a < 
recorded as fulling on those davs is remarkably small, indeed under the 
the year, for onto!’ 1G5 falls (tlin day as well as month of fall being known ‘ 
four have fallen between the 9th and Nth dap of August and Novonher. •• 
aerolitic and (luminous) meteoric epochs also would appear to differ,* 1 ■ 
ception of the 29th of November. From this circumstance it scans j ,rol f 
aerolites, and the majority of luminous meteors (especially periodic and con io 
ones), are resolvable into separate classes ; and in corroboration of * |||S 1 ,■ 
mentioned, that, while the number of aerolites whose falls have been rcco 
about equally divided fur the first; as for the second half of the year. th»'» ' ■ 
from being the case with luminous meteors, by far the larger numbers o ^ 
observed during the second half of the year, viz. from July to Decemner. 
then, wc consider aerolites as belonging to asteroids, with orbits 5 w ■ 
earth s, and partaking of the nature of true though minute planet?, , 
luminous meteors may be considered as having characters more in ( 
comets. It has been shown by several astronomers, as Olmsted, 1 16 . ’ rt h\ i 
others, that the majority of periodic meteors have orbits inferior k j nct 
then- perihelia near the planet Mercury. Mr, Greg concluded, after n ; , 
observations in favour of the self-luminosity of meteors, by lU : 
of their having a nature less dense than that of aerolites, but denser 
comets, and that it ia not improbable they have a fluid or viscid nature. 
On the Variation in the Rates of Chronometers. 
By Joiiv Hartnup, R.R.A.S., Liverpool. 
At the meeting Of the British Association in this town in e t ],e 1 ■*; 
that body, on the subject of a nautical observatory, was re* _ Memoii* 1 ^ 
Council, and referred to u special Committee. It in stated brought '* 
among the various objects of interesting inquiry which have 1 fflincr ci»i 1 
the British Association at their visit tu this large and enterprising the*.'. ' 
is e condition of nautical astronomy in the merchant service - ^ 0 (|it'< 
cation of which is decidedly the most important to mankind. , js gC j C BCt 
property which iB annually caused by a defective knowledge 0 r er ectinS * 
astonish, were it publicly known." After urging the importance or ^ *1 
ticaJ observatory, the objects of such an establishment in a ! wr f j irfln onif trr \' 
be the accurate knowledge of Liverpool time, and the care ^ sU ic 
n port, so that a captain when he sails may receive his chron , k ; 
their error and rate, which at present he cannot do. In this the i* ^ - 
of ‘ hs paragmg the chronometer-makers of Liverpool. ^inin* 
* J ,‘|I* Lou<1 °»'the times obtained from celebrated makers have " 
n nd nr S W ,° mm “ tes mi ght have caused a wreck." I have f** 
avi^Hnnh ‘r lhat h °1 ,eB ' vcre entertained of an irnp^'^Uing- ^;. , 
having recourse to more accurate means of rating an b & 
Messrs™ crnpl0 .y cd in merchant service. In “ cC “ 
the memorial the corporation established ahrst-raR » 
ofihrnnnmSr' ^ " 0W operation, so far as regards^ * l 
of chronometers, for nearly ten years; and the very active ^ 
Association in the recommendation of its establishments at its fir 
