674 



PHYSICAL FORCES. 



The largo and wide-spread surface supply of pe- 

 troleum of a past age over northwestern Penn- 

 sylvania and the southern part of western ISTew 

 York has long since, save at a few points, dis- 

 appeared. It is stated that few, if any, of the 

 old salt wells of the Sandy, Kanawha, Alleghany, 

 Muskingum, and other valleys in which these 

 Lave been worked, have been kept at a good 

 yield, except by deepening them from time to 

 time ; and that, at such times, usually new sup- 

 plies of gas and oil, as well as of brine, have 

 made their appearance. It is already noted 

 that along Oil Creek fewer of the new borings 

 afford spouting wells than was the case in 1861 

 and 'G2 ; while, further, the most violent blow- 

 ing and spouting wells of that period have be- 

 come comparatively quiet. It may be added, 

 that generally the flow of the best flowing wells 

 has not continued more than about eighteen 

 months. Though in a good proportion of cases 

 the pumping wells of the Oil Creek and con- 

 tiguous districts are quite regular in their yield 

 for a long time, yet very many such that once 

 yielded largely have finally given out. Indeed 

 it is found that, as a general rule, all the older 

 wells, flowing or pumping, have tended grad- 

 ually to a greatly diminished yield of oil, 

 while many, as just intimated, in time fail 

 altogether. In some instances, productive 

 wells suddenly cease to afford oil. 



It appears safe to state that, as a rule, the 

 value of oil-producing property is materially 

 impaired by any causes which lead to the con- 

 sumption or discharge of large quantities of the 

 imprisoned gas, or which, as in the case of the 

 inflow down abandoned wells, allow of the free 

 introduction of water into the oil reservoirs. 



In addition to authorities already named, 

 some information upon many points touched on 

 in this article, has been derived from the vol- 

 ume entitled " All about Petroleum " (N"ew 

 York, 1864), and some also from other sources. 



PHYSICAL FORCES. The investigation 

 into the nature and relations of the physical 

 forces continues with unabated and increasing 

 earnestness. It seems to be generally agreed 

 that the dynamical aspect of natural phenome- 

 na is the one to be mainly considered in future. 

 Facts of force and power have been long and 

 closely observed ; they now require to be com- 

 bined. The need is felt for a philosophy of 

 energy sufficiently valid and comprehensive to 

 explain the connections of the forces, and reach 

 propositions of sufficient universality to cover 

 all the cases of the exercise of power. 



The general problem may be conveniently 

 considered in a twofold aspect : first, respect- 

 ing those movements of the minute portions of 

 matter in which all molecular force is now be- 

 lieved to consist ; and, second, the relations 

 among the radiant forces. 



As respects heat, it may now be regarded as 

 well established that it does not consist in a 

 peculiar fluid, but in the movements of the 

 atoms or minuter portions of matter. Nothing 

 needed to be ad^.ed to the original and decisive 



experiments of Count Rumford to sliow the 

 complete futility of the old view, and fix the 

 conviction that heat is precisely what he called 

 it, a mode of motion. The conception of heat 

 as a calorific fluid was abundantly adequate in 

 the earlier stages of science, while yet material 

 ideas were dominant, and the physicist held 

 that his chief work was to determine the quali- 

 ties and quantities of matter. But when con- 

 ceptions of force had gradually grown into 

 prominence, and from considering the charac- 

 teristic properties of the various forms of energy 

 the investigation advanced to questions of quan- 

 tity, to the quantitative relations and equiva- 

 lences of power, the whole subject assumed a 

 new aspect, and the utter deficiency of the old 

 hypotheses was at once apparent. Rumford's 

 experiments were, no doubt, completely con- 

 clusive, but they have been reenforced by a 

 train of varied and extended investigations 

 through the last half century, which places the 

 whole subject in a new and most interesting at- 

 titude. Having abandoned the idea that heat 

 is a peculiar substantive tiling, a view which 

 cuts off all rational possibility of linking it to 

 other dynamic agencies, the physicist holds 

 that it consists essentially in atomic move- 

 ments, and that all its phenomena are to be 

 accounted for on this principle. Thermotics, 

 in fact, or the science of heat, is at once but 

 a branch of the greater science of molecu- 

 lar dynamics; as heat, like any other force, 

 is never known, except through material 

 movement. As its various efforts all resolve 

 themselves simply into expansions or contrac- 

 tions, it certainly seems the most natural view 

 to dispense entirely with the machinery of hy- 

 pothetical fluids, and define it as simply a mode 

 of motion in the matter which manifests it. 

 Exactly what those atomic motions are in which 

 heat essentially consists, cannot be considered 

 as yet determined. The prevailing opinion, 

 however, among scientific men is, that it con- 

 sists in the simple oscillations of the atoms. It is 

 more universally held that material atoms are 

 never in absolute contact ; that they are set at 

 distances from each other, with comparatively 

 large interspaces, which admit of free motion. 

 Heating a body, then, would consist of impart- 

 ing to it additional molecular motion, by which 

 the atoms would be made to vibrate through 

 larger distances, causing expansion of the mass. 

 Cooling would be a loss of this vibratile motion 

 by which the body contracts ; while the com- 

 municability of heat in its various modes and 

 conditions, is but the communicability of mo- 

 lecular motion. 



It has long been held that light is but a mode 

 of motion, as is shown by the universal accept- 

 ance of the undulatory hypothesis. Whether, as 

 is commonly done, an ether be assumed as the 

 medium of the undulatory movement, or wheth- 

 er, in accordance with the views of some, the 

 conception of an ether be held as unwarrantable, 

 and the undulations are assumed to take place 

 in ordinary matter, it seems to be substantial^ 



