182 Transactions. — Miscellaneous, 
the two retreating bodies will in many cases cause one or both of them to 
be attracted back to the coalesced mass; but as the foree which produces 
this return is partially due to the other retreating body, and for reasons 
already mentioned, the returning body will not necessarily come into 
collision with the coalesced mass, but may revolve around it producing 
double stars, or, if both bodies returned, triple stars, and in many cases the 
coalesced mass would also separate and produce even quadruple, or still 
higher multiple stars. I need not say that many thousands of multiple 
stars exist. Generally the returning stars, although sometimes of greater 
magnitude, would be of less luminosity, but this body would collect much 
of the matter revolving around the more luminous body, and so have its 
own temperature raised. In the case of nearly complete collision, the two 
pieces leaving the coalesced mass might reasonably be expected to break 
into pieces. Tt is possible to show that the rotation of each of these pieces 
must generally be in the same direction as the rotation of the coalesced 
mass, and that most of the forces acting would tend to produce a system 
resembling the solar system. 
Nebula. 
I have already shown how a ring nebule may be produced by a case of 
partial collision. The cometic nebule would be produced when a high 
resultant velocity was produced in the coalesced mass. It is not difficult 
to conceive that in the collisions of approximately equal bodies the coalesced 
mass might separate chiefly into two other larger masses, and produce 
double nebule, and ultimately double stars revolving around each other. 
Again, a case of almost complete coalescence appears competent to give rise 
to the conditions we observe in the spiral ‘nebulw, as it will be seen that 
rotation wil be very slow in this case, and the expulsion of matter 
irregular, although it must be confessed that it seems probable that 
generaly a large nucleus of eontinuous nebule would be produced. At 
the same time possibly higher power observations may show this to be the 
case. 
Art. IX.—On the Calculation of Distances by means of Reciprocal Vertical 
; Angles. By C. W. Apaus. 
[Read before the Philosophical Institute of Canterbury, 12th September, 1878.) 
Tar distance between any two points on the earth's surface may be found, 
if the angle subtended by those points at the centre of the earth is known, 
