SOUNDING 



5446 



SOUSA 



Speed of Sound. Nearly every one has tried 

 the experiment of counting between a stroke 

 of lightning and the peal of thunder which 

 follows, to learn how far away the flash oc- 

 curred. If you count in seconds and divide 

 the result by five, you will have an approxi- 

 mately correct idea of the number of miles, 

 for sound travels through the air about a fifth 

 of a mile in a second, and light covers 186,000 

 miles in a second, which for practical purposes 

 is an instantaneous rate. The temperature of 

 the air affects the speed of sound; at the 

 freezing point it is about 1,090 feet per second 

 and increases about two feet for every degree 

 Centigrade, or a little over one foot for every 

 degree Fahrenheit. 



When There's No Ear to Hear. A man on 

 a hilltop sees a large tree fall half a mile away, 

 but no other evidence of its fall reaches his 

 senses. He sees a rushing cataract still farther 

 away, but except for sight has no evidence of 

 its existence. If he says the falling tree and 

 the waterfall make no sound, is he right? If 

 the sound waves of the air do not reach the 

 ear, is there sound? Imagine a tree falling a 

 hundred miles from a human being, or as far 

 from one of the lower animals or any other 

 form of animal life. Would it make a sound? 

 Does sound issue from a telephone ringing in 

 an empty house far from other buildings? 



There are few livelier questions for discus- 

 sion, but even scientists do not agree upon the 

 answer. C.H.H. 



Related Subjects. The following topics in 

 these volumes may be consulted 'n connection 

 with this article on sound : 

 Ear Light 



Echo Music 



Harmonics 



SOUND 'ING, the process by which ocean 

 depths are determined. In very early times 

 attempts were made to find the depth of water 

 for the purpose of aiding navigators, but it was 

 not until the nineteenth century that instru- 

 ments were invented which could be success- 

 fully used for deep-sea sounding. The intro- 

 duction of submarine cables made necessary a 

 detailed knowledge of the contour of the ocean 

 bed and greatly stimulated efforts to perfect a 

 satisfactory sounding machine. The simplest 

 sounding device is the plummet, a lead shaped 

 like a window weight, to one end of which a 

 stout cord is attached. It is thrown into the 

 water, and as it sinks it draws the cord with 

 it, which, being marked in feet, shows the 

 depth. See PLUMMET. 



For deep-sea and scientific purposes the 

 plummet is replaced by a diving rod, which is 

 a hollow cylinder with valves at the top and 

 bottom, opening upward. It is weighted with 

 iron sinkers slightly conical in shape, with a 

 cylindrical hole through which the diving rod 

 easily passes, and these are so attached to the 

 head of the rod that they become loose and 

 slip off when it strikes the bottom. The 

 hempen cord of the common plummet is re- 

 placed by a fine piano wire, which passes over 

 a grooved wheel, and the depth is measured 

 on the principle of a cyclometer. As the rod 

 is hollow, it brings up a core of mud from the 

 bottom. The valves which were open in the 

 descent close and preserve the contents, while 

 the sinkers remain behind and are lost. 



SOURIS, soo'ris, a town in the southwestern 

 corner of Manitoba. It is on the Souris River 

 and on several branches of the Canadian Pa- 

 cific Railway, twenty-four miles southwest of 

 Brandon and 151 miles west of Winnipeg. The 

 word souris is French for mouse, and was given 

 to the town and the river because of the many 

 muskrats in the river. Plum Creek, so called 

 for the wild plums which grow on its banks, 

 empties into the Souris River at this point. 

 The town was founded in 1882. Population in 

 1911, 1,854; in 1916, 1,845. 



Souris is a railway division point, and has 

 Canadian Pacific repair shops. Among the 

 largest manufacturing establishments are a 

 flour mill, a furniture factory, and a foundry 

 and machine shop. The shipment of grain 

 raised in the surrounding agricultural district 

 is an important industry, as is shown by the 

 capacity (200,000 bushels) of the local ele- 

 vators. The town owns and operates its water- 

 works and electric light and acetylene gas 

 plants. The $50,000 postoffice, erected in 1912, 

 and the $45,000 collegiate institute, are splen- 

 did stone structures. 



SOURIS, a town in Kings County, in the 

 northeast part of Prince Edward Island, on 

 Colville Bay. It is on the Prince Edward 

 Island Railway, sixty miles almost directly east 

 of Charlottetown. Fishing, the leading indus- 

 try, is mostly for lobsters, but considerable 

 attention is given to cod, hake and haddock. 

 Sawmills and planing mills, cheese box and 

 motor boat factories are the only manufactur- 

 ing establishments of importance. Population 

 in 1911, 1,089; in 1916, about 1,500. 



SOUSA, soo'za, JOHN PHILIP (1854- ), 

 an American composer and bandmaster, was 

 born at Washington, D. C. He studied music 



