SCIENTIFIC SUMMARY. 
299 
¥ 
and faint, with slight signs of nuclear aggregation. No important ohscrva- 
tions have been made upon it. 
N’eiv type of Stnr-spectnwi. — Father Secchi announces the discovery of a 
fourth type of spectrum, which is presented by certain red stars. With some 
slight differences, this spectrum exhibits a close relation to that yielded by 
the flame of carbonic oxide. 
Aurorce Boreales . — An account of their recognised association with solar 
action, and the coincidence of their occurrence with the recent disturbed 
state of the solar photosphere, the auroral displays of the months of April 
and May last, may worthily claim a place in a summary of astronomical 
events. A singular feature was noticed in connection with the aurora 
which was visible on April 15 over the greater part of North America. 
Around the planet Mars there appeared a vacant space beyond which was a 
sort of glory ” surrounding the planet, and having radial bars extending to 
the horizon. The moon appeared like the head of a gigantic comet, the tail 
being composed of auroral streamers. During the continuance of the dis- 
play telegraphic communication was affected to a remarkable extent, a cir- 
cumstance which is now a recognized concomitant of auroras. 
The Voyage of the Jean BartJ — M. Faye has suggested the astronomical 
subjects which should be principally considered by those who will take part 
in the six months’ voyage of circumnavigation which is about to be under- 
taken in this vessel. He suggests that observations should be made of the 
Zodiacal Light in those regions where it shines more brilliantly than in our 
own hititudes. He points out that it would be advantageous if its contour, 
the portion of its axis, and other details of its manifestation, could be 
studied. Attention should be given also to those displays of shooting-stars 
which correspond to radiant points situated beyond the “ circle of perpetual 
apparition ” for our climate. The southern constellations ought to be ob- 
served ; and something might also be done to furnish useful information for 
the astronomers who will take part in observing the transit of Venus in 
1874. 
An Improved Method of Mounting Finders. — The bad adjustment of a 
finder is a constant trouble to the observer. Professor Piazzi Smyth wrote 
some time since to Mr. Browning “ that he thought some better plan for 
mounting and adjusting finders was much required.” Acting on this hint, 
Mr. Browning has devised a new and simple mode of mounting these 
auxiliary telescopes. The common plan is to have the finder placed in the 
centre of two rings somewhat larger than itself, and adjusted by means of 
three screws working through each ring, and pressing on bands whicli serve 
to strengthen the finder. The great objection to this plan is the complexily 
of adjustments depending on six screws. Almost equally objectionable is 
the plan of having a moveable “ stop ” carrying the cross-wires. Mr. 
Browning’s plan is easily understood and worked. If we consider that the 
axis of the tinder is to be parallel to that of the telescope, we shall see that 
two tilings are required. First, the twm axes must be in one plane ; secondly, 
they must be in the same direction in that plane. By Mr. Browning’s ar- 
rangement each of these requisites is adjusted for separately, by the simple 
movement of two screws placed opposite each other, one pair of screws at 
one end of the finder giving the requisite motion of that end at right angles 
