86 THE POPULAR SCIENCE MONTHLY. 



now, it has become necessary to purge religious "belief of dross 

 in the form of trivialities and superstitions. This has ever been 

 and ever will be the function of science. The essentials of re- 

 ligious faith it does not, it can not, touch, but it purifies and 

 ennobles our conceptions of Deity, and thus elevates the whole 

 plane of religious thought. 



It will not, of course, be expected of me to give, even in brief- 

 est outline, a system of reconstructed Christian thought. Such 

 an attempt would be wholly unbecoming. Time, very much 

 time, and the co-operation of many minds, bringing contribu- 

 tions from many departments of thought, are necessary for this. 

 In a word, it can only itself come by a gradual process of evolu- 

 tion. But from the point of view of science some very funda- 

 mental changes in traditional views are already plain. Of these 

 the most fundamental and important are our ideas concerning 

 God, Nature, and man in their relations to one another. 



■♦«» 



SOUND-SIGNALS AT SEA. 



By ARNOLD BURGES JOHNSON. 



THE difficulty in determining the true and exact direction of 

 the sounds we hear meets us in various ways. The hunter 

 hears the note of a bird, the hiss or whistle of a deer, and the 

 sound indicates identity and proximity but not direction. The 

 hunter waits for repeated renewal of the sound to ascertain its 

 exact position, and even then verifies his audition by his vision. 

 The hunter by his camp-fire may aim between the luminous dots 

 of reflected light, which he knows to be the eyes of a wolf ; but 

 he would scarcely be able to aim at or even very near that spot 

 on simply hearing the howl from the wolf that owns the eyes. 



The plainsman hears a shout in the distance. He may recog- 

 nize it as the voice of a comrade, and fix the general direction 

 as north, east, south, or west, but hardly more. He may shout 

 back, and the two may come together; but if it be dark and 

 there is no fire or other signal, the shouting back and forth must 

 be frequently repeated, and varied from a simj)le to a complex 

 sound, that each may correct the error of his own audition, 

 eliminate his personal equation, and the sound will appear to 

 swing, pendulum-like, right and left, with shorter and shorter 

 stroke, till the comrades come together. 



The average child, returning from school, on entering the 

 house calls, " Mamma ! " The mother, perhaps, replies, " Yes ! " 

 " Where are you ? " is the next question, and the reply informs 

 the child not only as to the floor, but as to the room in which 



