Polytechnic Association. 881 



increasing the effect. At last the left-hand barrel is fired and an 

 explosion takes place. 



Mr. R Weir — If the shot is next the charge the first pressure upon 

 it is, perhaps, thirty pounds to the square inch ' y if it is placed off 

 further, the first pressure may be two or three times as great. 



II. Gunpowder Gauge. 



The principle suggested by Tresca's experiments on the flow of solid 

 bodies, has been applied by M. le Commandant de Keffye to the deter- 

 mination of the pressure in the bore of large guns. A cylindrical 

 hole, bored into the gun, is filled by a block of lead, supported behind 

 by a steel block, through which is a small cylindrical hole. "When 

 pressure acts on the lead, a portion of it is forced into the hole in the 

 steel block. The volume of lead found in the cylindrical cavity after 

 the gun has been fired is the measure of the pressure in the bore of the 

 gun. 



III. Effect of Fasting. 



Prof. Seegan has communicated to the Viennese Academy of 

 Science the results of investigations upon the metamorphosis of tissue 

 during fasting. The subject of his experiments was a young girl, 

 who, in consequence of a stricture of the esophagus, was only able to 

 consume very small quantities of nourishment. During a whole 

 month her daily food was but thirty-five grammes of milk, and about 

 twenty cubic centimeters of water. A teaspoonful of this mixture 

 was taken every hour. After lasting four weeks the difficulty of 

 swallowing gradually disappeared, and the quantity of milk taken 

 daily rose to 210 grammes. The author gives a full account of many 

 interesting results obtained, only one of which need be here stated, 

 namely : that the metamorphosis of the albuminates, which was prin- 

 cipally supplied from the muscles, so far as measured by the excretion 

 of urea, during fasting, bears the proportion to the normal meta- 

 morphosis of 1:4 or 1:5. 



IV. The Flow of Liquids. 

 Prof. Colding gives, in the Copenhagen Transactions, his inves- 

 tigations of the law of the motion of water in pipes and conduits, and 

 has also applied his results to ocean currents. His method is to deter- 

 mine the motion of liquid threads, that motion vailing with the depth 

 when water flows over a plane surface. The formulae now generally 

 used are founded on the assumption that water moves in plane layers 

 at uniform velocity. These formulas are known to be defective. 

 [Inst.] 50 



