7o8 



THE POPULAR SCIENCE MONTHLY. 



and the jaws of a young peccary {Dicotylcs 

 nasutus), are of extinct animals. None of 

 the remains have been identified as posi- 

 tively pertaining to our domestic animals, 

 unless two of the teeth may be those of a 

 foetal or new-bom horse. The vegetal re- 

 mains include a few small fragments of 

 charcoal and seeds of dogwood, pig-nut, 

 and walnut. Remains of human work were 

 found a large stone celt of hard brown 

 slate, from the bone-earth some distance 

 within the cave ; five bone awls, some of 

 them gnawed ; the prong of an antler worked 

 so as to be barbed on one side ; a needle of 

 bone resembling a crochet-needle ; a fish- 

 hook of bone ; and a cone-shell, of a species' 

 found on the western coast of Central Amer- 

 ica, bored through the axis as a head. Pro- 

 fessor Leidy has, since exploring this cave, 

 examined a collection of bones in the Mu- 

 seum of the Philadelphia Academy of Natu- 

 ral Sciences, which were found more than 

 thirty years ago in the Durham Cave, Bucks 

 County, Pennsylvania. The bones are of 

 the same character as those of Hartman's 

 Cave. 



Temperatnre of the Breath. We have 

 before noticed the fact that the effect of 

 breathing upon the bulb of a thermometer 

 through several folds of flannel is to raise 

 the temperature of the thermometer several 

 degrees above that of the mouth and body, 

 and the theory suggested by Dr. Dudgeon 

 to account for the phenomenon, that the 

 breath is the vehicle by which superfluous 

 heat is removed from the body. Dr. Wil- 

 liam Eoberts pronounces this theory unten- 

 able, and indicates, as an experiment that 

 will show it to be fallacious, that a naked 

 thermometer placed in the mouth, and 

 breathed upon by expiration, will hardly 

 rise to the normal temperature of that 

 part of the body. He suggests another 

 explanation, which has been accepted by 

 Dr. Dudgeon. It is, that the temperature of 

 the thermometer is raised by the action of 

 the specific heat which is liberated by the 

 condensation of the moisture of the breath. 

 If the experiment of breathing is repeated 

 with the same thermometer and flannel at 

 short intervals, the degi-ee to which the 

 temperature rises decreases with each repe- 

 tition till at last only a slight effect is pro- 



duced. This is because the flannel, already 

 charged with moisture, has a diminished ca- 

 pacity for condensing more moisture with 

 every new trial of the experiment. If, on 

 the other hand, the flannel is thoroughly 

 dried before beginning the experiment, an 

 increase of temperature to 115, or several 

 degrees higher than the highest noted by 

 Dr. Dudgeon, is indicated immediately on 

 breathing upon it. The capacity of the cloth 

 for absorbing moisture has been largely in- 

 creased by the drying. 



Perforation of Lead Pipes by Rats. 



We give herewith another well - authenti- 

 cated case of the perforation of a lead 

 water - pipe by rats, kindly furnished by 

 Mr. Henry C. Hallowell, of Sandy Spring, 

 Maryland. Mr. Hallowell writes : " As the 

 confirmation of a statement is sometimes 

 of value, I send a hasty sketch of a piece 

 of lead pipe in my collection that has been 

 gnawed by rats, as described by Dr. Wil- 

 liam Eassie, in " The Popular Science 

 Monthly" for January. The pipe is one 



Lead Pipe gnawed by Eats. 



and one eighth inch in diameter, and the 

 lead three sixteenths of an inch thick. The 

 hole is three inches long, and appears to 

 have been made to get to water." 



The Mannfaetnre of Indigo in Bengal. 



Indigo is almost entirely obtained from legu- 

 minous plants of the genus Indigofera, of 

 which two principal species are grown in 

 India and America. The factories in Ben- 

 gal are provided with filters, presses, a 

 boiler, drying-grounds, reservoirs, and vats 

 for fermentation. The plant is cut in the 

 morning, and taken to the factory. In the 

 evening it is loaded in the vats, tightly 

 pressed down, and then submerged in water 

 and exposed to a process of fermentation 

 for from nine to fourteen hours. The prog- 

 ress of the fermentation is tested by draw- 



