346 THE FARMER AT HOME. 



lected, covered with turf, and then set on fire, the resinous juice 

 which would have been dissipated in the open air, may be collected in 

 a suitable receptacle beneath. In this way, tar and pitch, two well 

 known articles of commerce, and both of a resinous nature, are usually 

 procured. From a shrub that grows in Palestine and Arabia, is ob- 

 tained a resin long celebrated for its medical virtues. It is the Balm 

 of Gilead, so frequently alluded to in sacred history, and it is highly 

 prized by the Turks, who prohibit its exportation. 



No kind of wood is sc durable as that in which the resinous secre- 

 tion abounds. It is rarely injured by those insects which devour the 

 hardest timber, and the insolubility of resin most effectually secures it 

 from the destroying agency of water. As a proof of this fact, it has 

 been observed that the cypress gates of Constantinople, erected by the 

 Emperor Constantine, were found undecayed a thousand years after 

 they were built. It is owing to this secretion that pine is more dura- 

 ble than the hardest oak, though at the same time it contains much 

 less of the woody fibre, on which the value of timber usually depends. 



RESPIRATION. In Physiology, that function of animal bodies, 

 in which the air, either in its elastic state, as it constitutes the atmos- 

 phere, or held in solution in water, is brought into contact with some 

 organ or organs, undergoing alterations in its own constitution, and 

 producing changes in the nature of the animal fluids, which are essen- 

 tial to the continuance of life. In the mammalia, birds, and reptiles, 

 the respiratory organs consist of lungs, that is, of membranous cavi- 

 ties, differently constructed in the three classes, but agreeing in the 

 circumstances of alternately receiving and emitting a Dortion of atmos- 

 pherical air. This alternate ingress and egress of air constitutes pro- 

 perly what is called in common language breathing, to which the 

 philosophical term respiration is synonymous. 



Although the structure of organs in fishes and insects is so different 

 from that which we find in mammalia, birds, and reptiles, they per- 

 form an analogous office, answer the same general purposes in the 

 animal economy, arid are considered equally in the light of organs of 

 respiration ; this term being employed now to denote the general effect 

 produced by these various organizations, without any reference to the 

 means through which it is produced ; although it was originally ap- 

 plied to the passage of the air to and from the lungs, when the results 

 of that process were unknown. 



The functions of the respiratory organs are closely connected with 

 the other great processes of the animal economy. The heart, brain, 

 and lungs, more particularly influence each other, and present, in their 

 mutual relations, numerous and highly interesting considerations for 

 the physiologist. 



REVOLVING HAY RAKE. Every person familiar with the 

 routine of labor on the farm, must be aware of the excessive toil and 

 the frequent pressing urgency for despatch in the season of hay making. 



