358 REPORT—1874. 
List of Cometary Radiant-points agreeing approximately with those of known 
Comet’s Cometary- Cometary radiant- 
: : p 
No Comet and its ae a shower point (1875). R nie 
Node. Date wae 
ornearthe| (4 875) 
Node. | (875) | Ra. | Decl. 
fo} ° 
BOWE UBS: Fines scnnee 0:80 Dec. 5 200 +69 | Hiliptic orbit period 70-7 years; 
TOE 23) ta sxccees 1:10 » 20 220 +76 naked-eye comet with tail 2° 
MSMR eicc nkc cnn 1:07 » 20 221 +T. long. 
PIO a LGSUR ES te 2d.s cok aeniee 0-94 See 133 +22 | Comet with tail of 70° to 90° ; 
Weiss ...... ie airaenes 0-96 » 26 132 +21:4| approached almost to grazing 
the sun. Supposed by Halley 
to be periodic, but no definite 
| period can be assigned. 
Dl | TS46r Vail ws: ...2... 1-09 ep Wks 200 + 4 |A naked-eye comet; elliptic 
; orbit ; period 400 years (?). 
HELMED es: Troe. 0:87 > 28 169 —36 | Moved rapidly; a hyperbolic | | 
orbit has been assigned to it. ] : 
present form to be, it is yet in the main a fairly correet and well verified 
representation of the real or apparent coincidences between meteor-showers 
and cometary orbits (to the close of the year 1866) that can at present be 
offered for purposes of preliminary use. The groups of comets as well as of 
meteor-showers that it presents, and the apparent replacement in some cases 
of formerly existing groups of comets (as those of 1264 and 1556 a.p., No. 12) 
by present well-established star-showers, together with the gradual changes, 
dismemberments, or decrease of brightness sometimes traceable in the come- 
tary groups, are features of the list which recommend its introduction at the 
close of this Report, with a view to its further consideration by the Com- 
mittee in future communications, with such corrections and amplifications as 
its present condition may require. 
Copies of a paper on the “ Latent Heat of Expansion, in connexion with 
the Luminosity of Meteors,” presented to the American Philosophical Society, 
March 6th, 1874, were forwarded to the Committee by its author, Mr. B. V. 
Marsh, and have received their special attention. By means of a somewhat 
new mode of considering the heating-effect of compression on air, Mr. Marsh 
arrives at conclusions which are substantially the same as those generally ad- 
mitted with regard to the high temperature and intense ignition developed by a 
meteorite in traversing the rarest strata of the atmosphere, and asks if such 
bodies traversing the outer limits of the sun’s photosphere, and thence pro- 
ceeding without sensible loss of their energy on their course, might not pro- 
duce, without much expenditure of actual mechanical energy, the enormous 
luminosity of its surface. Itshould, however, be observed that the immense 
quantities of heat emitted from it by radiation would not on this hypothesis 
be accounted for. 
