MISCELLANY. 



253 



above it, and the temperature is thus pre- 

 vented from falling as low as it otherwise 

 would. 



Trapping Wild-Tarkeys. There is a 



touch of cynic humor in a peculiar mode of 

 trapping wiid-turlieys in Virginia, as de- 

 scribed by a writer in Forest and Stream. 

 Having discovered one of the familiar haunts 

 of the birds, the trapper digs a trench 

 eighteen inches deep and about as wide, and 

 four or five feet long, with a slope from the 

 outer end deepening to the middle. A pen 

 of fence-rails is now built, the first rail being 

 laid across the middle of the trench ; this 

 is the width of the pen, and it has the length 

 of two rails. It is built to the height of 

 eight or ten rails and covered over with the 

 same. Some grain is now scattered around 

 and in the trench, and a large quantity with- 

 in the pen. The turkeys get on the train 

 of bait leading into the pen, and with heads 

 down, eagerly picking up the grain, they go 

 under tlie sill-rail in quest of food. Half a 

 dozen or so will perhaps enter in thus, and 

 then they find themselves imprisoned. They 

 go round and round to find an exit, but it 

 never occurs to them to look down, a,nA thus 

 they never find the passage through which 

 they entered. 



Rationale of the Welding of lion. The 



welding of iron and the regelation of water 

 are very ingeniously traced to the same 

 cause by Mr. M. Jordan. Faraday was the 

 first to observe the phenomenon afterward 

 called " regelation." By this term we im- 

 ply that when two pieces of ice are pressed 

 even very gently together, the temperature 

 being just below zero, they at once become 

 welded to each other. Of this Thompson 

 offers the following explanation : For all 

 bodies which, like water, have the property 

 of diminishing in volume as they liquefy, 

 pressure, which tends to bring the mole- 

 cules closer together, lowers the tempera- 

 ture of fusion. Consequently, when two 

 pieces of ice are rubbed against each other, 

 fusion takes place between the surfaces in 

 contact, at a temperature below zero. But 

 as soon as the pressure ceases solidification 

 is again produced, and the pieces are welded 

 together. With iron, observes Mr. Jordan, 

 the case is the same. The two pieces to 

 be welded together are brought to a white 



heat, i. e., more or less near to the fusing- 

 point. The repeated blows of the ham- 

 mer, or the pressure of the rolls, lowers 

 the point of fusion, causing a superficial 

 liquefaction of the parts in contact, and 

 thus welding the masses together; and this 

 because, like water, iron dilates in passing 

 from the liquid to the solid state. " The 

 careful comparative study of these two 

 bodies," adds Mr. Jordan, "even though at 

 first sight apparently so dissimilar, cannot 

 fail to furnish results of great interest to 

 the metallurgist. The work of the puddler 

 is also based upon the same phenomenon 

 as that of welding. When the puddler 

 forms his ball in the furnace, it is done by 

 rolling together or aggregating the crystals 

 of iron as they form in the mass of melted 

 iron and slag. In other words, the semi- 

 fused crystals are welded or regelated to- 

 gether by the mechanical action of the pud- 

 dler." 



Propagation of Waves in Liquids. At a 



late meeting of the Paris Physical Society, 

 M. Marey exhibited certain apparatus which 

 he has employed in studying the propaga- 

 tion of waves in liquids. His method con- 

 sists in producing, at a given point in an 

 India-rubber tube filled with water, a sudden 

 compression or dilatation, either by press- 

 ing on the walls of the tube, or by means 

 of a piston. Small clips arranged along the 

 tube at equal distances from each other 

 signal the passage of the wave of compres- 

 sion or dilatation to a registering appara- 

 tus. In this way M. Marey has found that 

 the velocity of the waves decreases with 

 the size and increases with the elasticity of 

 the walls. The density of the liquid has 

 also some effect, but this is not of sufficient 

 importance to be taken into account in ap- 

 plying this method of observation to physi- 

 ology. 



Restoration of Faded Writings. Very 



often paper and parchment documents are 

 illegible owing to the ink with which they 

 were written having faded. The Revue In- 

 ditstrklle gives a very simple method of re- 

 storing to the ink its color. It is as follows : 

 First, wet the paper and then pass over it 

 a brush dipped in a solution of ammonia 

 sulpho-hydrate. The writing quickly re- 

 appears, the characters being of a very deep 



