CHAPTER XLII. 



NEW ASTRONOMICAL APPLIANCES. 



A CELESTIAL INDICATOR ASTRONOMICAL OR COSMOGRAPHICAL CLOCK 

 A SIMPLE GLOBE A SOLAR CHRONOMETER. 



HAVING said something concerning astronomy, we will give a few 

 instructions respecting the instruments not already described, and make 

 some observations, supplementing our directions in the previous chapter, 

 for many people will be glad to learn how to read the evening skies. 



Here we have an apparatus which will prove useful to amateurs ; it 

 is a sort of celestial indicator by Mauperin, and will facilitate the finding of 

 every star or constellation, when the apparatus has been made ready by 

 pointing the rod, T, in the direction of the object it is desired to view. 

 This rod is mounted upon a rod, S, and is movable upwards or downwards 

 or sideways, and in the last-named movement it will carry with it an 

 indicator, I, which slides over the chart or diagram of the heavens. The 

 two arms of this indicator are always parallel to the plane of the rod, T, 

 no matter in what position they may be on the chart or the inclination 

 of the rod. The extremities of this rod are terminated by an eye-slit, and 

 by a crescent respectively. 



When the apparatus is set, all one has to do is to look through the 

 eye aperture, O, and view the star which we have chosen in the centre 

 of the crescent, c. This star will be found named in the space between the 

 arms of the sliding indicator, i. 



It is easy to perform the operation inversely that is to say, to find 

 in the sky, by means of the sighting-rod, T, the stars we have chosen on 

 the chart between the prongs of the indicator. The chart represents 

 exactly the heavens as we see them, and this new mode is opposed to 

 the manner generally adopted with celestial charts, and is very important, 

 for it obviates the necessity of holding the map above one's head, its face 

 downwards. 



As we have already showed, it is not difficult to find the Polar Star 

 and the Great Bear. The latter is readily recognised by its seven stars, 

 and the Lesser Bear glides around the pole as shown in the diagram on the 

 preceding page (fig. 629). Now let us see how the celestial indicator will 

 work. 



Let us take the apparatus into the open air, and place it upon its 



