February 8, 1889. J 



SCIENCE. 



109 



likening them to human pirates, and berating Deer Run for what 

 it has done, let us look at the affair from the point of view that a 

 well-disposed river would take. 



When this district was lifted from its former lowly estate, the 

 streams found a new task set before them. They at once set to 

 work at it with the best disposition in the world. But, in their im- 

 maturity, they accepted without question such guidance as the faint 

 relief of the surface afforded, only to discover later on that the 

 primitive division of territory was unadvisable as a permanency, 

 because it was not adapted to the best accomplishment of the work 

 assigned to them. It is found that a re-adjustment of boundaries, 

 in certain cases, will allow a more economical transportation of 

 land-waste to the sea by better-arranged channels ; and, when this 

 becomes apparent to a stream, it at once obeys its new opportunity, 

 whatever force of habit it may theretofore have had. If the ideal 

 -of a stream's life were always to persevere in the channel that it at 

 tirst selects, this readiness to change its course would be called 

 fickleness ; but when we perceive that the true ideal of a stream's 

 life is to carry towards the sea its full share of the waste of the land 

 that its river system drains, then we may recognize a virtuous wil- 

 lingness to the performance of duty in this immediate forsaking of 

 -an old course, and adoption of a new one, where its work can be 

 done better and quicker. It is the unwisdom of youth that is thus 

 corrected by the better choice of maturity, and many a river has 

 thus improved its early ways. It is undoubtedly true that Deer 

 Run has taken something of what once belonged to the Perkiomen, 

 but it was not seriously that the name of a river-pirate was given 

 to it. W. M. D. 



A POPULAR OBSERVATORY. 



A FEW months ago a company was formed in Berlin, the aims 

 and purposes of which are well worth being widely known. The 

 company is named " Urania," and it was established for the pur- 

 pose of diffusing the interest in the phenomena of nature. Some 

 of the most prominent German scientists are the promoters of this 

 enterprise, the plan of which originated with the distinguished as- 

 tronomer Professor W. Foerster, who explains the objects of the 

 company as follows : The object of the society is to promote 

 knowledge. In order to inculcate knowledge, it is necessary to 

 educate man to use his mental powers. Therefore institutions for 

 the diffusion of knowledge can only be successful when they try to 

 teach how to use one's mental powers. The society has limited 

 its work principally to astronomical, geographical, and physical 

 phenomena, and for reaching its object has established a great 

 popular observatory, which will be a model for all similar institu- 

 tions, and publishes a journal, Himmel iitid Erde (Berlin, H. Pae- 

 lel), which is beautifully printed and illustrated, and gives, in a 

 popular form, reports on astronomical and geographical phenomena 

 and questions. 



The popular observatory, of which we reproduce the plan, is di- 

 \ ided into three sections, — - the rotunda, which forms the foundation 

 of the observatory proper ; the large hall, in which instruments and 

 microscopes are e.\hibited ; and the scientific theatre. It is the 

 plan of the founders of this institute to benefit the general public, 

 which embraces uneducated as well as educated persons. There- 

 fore the methods of instruction are varied according to the intelli- 

 gence and education of the various classes. The scientific theatre 

 forms the lowest stage, on which the results of exact investigations 

 are presented in as attractive a form as possible, in order to give a 

 stimulus to intelligent observation. Solar and lunar eclipses, 

 comets, and meteors are shown to the spectator ; the scenery rep- 

 resenting beautiful and characteristic landscapes of the parts of the 

 globe in which these phenomena were seen. Thus the desire is 

 aroused to understand the origin of these phenomena, which, only 

 a few centuries ago, were considered as forebodings of evil. These 

 views are accompanied by lectures calling attention to the peculiar- 

 ities of the phenomena observed on the scene. Among others, a 

 series of astronomical panoramas has been prepared for the pur- 

 pose of explaining the phenomena of solar eclipses. 



At the commencement of the lecture the stage represents a land- 

 scape near Berlin, at the beginning of the total eclipse of Aug. 19, 

 18S7. At that time unfavorable weather prevented the remarkable 



phenomena from being seen, to which attention had been called in 

 newspapers and journals. In the theatre all phenomena of the 

 eclipse will be shown as they would have happened in clear weather. 

 First the landscape will be seen in the light of the early dawn ; 

 then the sun will slowly rise on the horizon in the shape of a cres- 

 cent between purple clouds. The crescent grows narrower rapidly 

 until the dark shadows of the eclipse appear. After two minutes 

 the character of the illumination changes again, and soon the land- 

 scape is seen lighted by the clear sun. 



While the lecturer explains this phenomenon, the scene changes, 

 and the spectator is transported to a place at some distance from the 

 earth. The huge globe rotates in front of the zodiac, whose signs 

 form the background. The moon, moving through the sunlight, 

 throws its shadow upon the planet, and it is seen crossing the con- 

 tinent of Europe. It is at once understood how the eclipse origi- 

 nated. We continue our journey and reach the moon. We see its 

 desolate mountain ranges. There is deep night in the valleys, while 

 the summits of the mountains are lighted by the rising sun. On 

 the starry sky the earth is seen, giving some light to the parts of 

 the moon over which the sun has not yet risen. On the earth a 

 small dark dot is seen, the point of the shadow of the moon, and 

 its track shows the region where the eclipse is visible. Our 

 journey is continued toward the sun and the planets, the surfaces 

 of which are shown according to the result of the most recent in- 

 vestigations. 



A higher stage of instruction is given in the exhibition hall, in 

 which instruments, apparatus, and arrangements of various kinds. 



are exhibited, for the purpose of explaining physical phenomena. 

 The composition of sounds, particularly those of speech, are exhib- 

 ited. The wonderful phenomena of light ; its enormous velocity ; 

 its composition of numerous colors, which makes nature appear so 

 beautiful ; the wonders of the spectroscope, which betrayed the 

 chemical composition of the celestial bodies, and is at present used 

 in many industries, for instance, in the Bessemer process, and in 

 the examination of wines and other liquids regarding their adultera- 

 tion ; the phenomena of polarization and their application in the 

 manufacture of sugar, — all these will be shown and explained to 

 the visitor. In another section of the hall the phenomena of heat 

 will be explained. Models of machines will be exhibited here in 

 great numbers. In still another part of the hall electricity and 

 magnetism, and their extensive applications in manufactures and 

 as a means of rapid communication between distant places, will be 

 shown. Furthermore, fifty microscopes will be placed in this hall, 

 in which the use of this powerful help to scientific investigation 

 will be explained. 



Instruments of precision will be exhibited in the same hall. From 

 the latter a staircase leads to the observatory, passing the lecture- 

 room. Here astronomical and microscopical objects will be shown 

 by means of the lantern, and a lecturer will call attention to the 

 characteristic features of each object before it is seen through the 

 telescopes and microscopes. 



