68 



MEETING OF THE BRITISH ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE. [1853 



1o 72° W., or about the same distance West of New York. To .each 

 of these six divisions he directed attention, pointing out the conclu- 

 sions to be derived from each. The curves approaching each other 

 and running nearly parallel through the western hall' with great regu- 

 larity, shoeing the variations and range to be much less, while through- 

 out the eastern half the widening- of the distance/and the irregular 

 form of the extreme curves show ed the influences of the two currents 

 very remarkably, 'i lie author then proceeded to draw conclusions, 

 showing that sometimes the cold current from the north plunged be- 

 neath the warmer current from the south. Sometimes they divided, — 

 the colder keeping in shore along the American coast, the ether keep- 

 ing out and forming the main Gulf-stream. Sometimes where they 

 met they interlaced in alternating stripes of hot aud cold water; some- 

 times their meeting caused a deflexion, — as, where oue branch 

 of the Gulf-stream was sent clown to the south-east of Europe and 

 north of Africa aud another branch sent up past the British Islands to 

 Norway aud Scandinavia by the the. Polar current setting down to the 

 east of Newfoundland. The author next proceeded to consider the 

 uses in the economy of nature of these great oceanic currents. The 

 first that he noticed was the equalizing and ameliorating influence 

 which they exercised on the temperature of many countries. Of this 

 he gave several examples. Thus, our own country, though usually 

 spoken of as a very variable climate, was subject to far less variations 

 of range of temperature than many others in similar latitudes, — which 

 was chiefly from the general influence of the northern branch of the 

 Gulf-stream settiug up past these islands. He had himself on one oc- 

 casion in the month of November known the temperature to rise 

 no less tban52° in forty-eight hours, — have previously descended in a 

 very few days through a still greater range; while in these countries 

 the extensive range between mean summer and winter temperature 

 scarcely in any instance exceeds 27 °,and in many places doesnot amount 

 to nearly as much. Another advantage derived from these currents 

 was, a reciprocation of the waters of high and low latitudes, — thus, 

 tending to preserve a useful equalizing of the salUiess of the waters, 

 which otherwise by evaporation in low latitudes would soon become 

 too salt to perform its intended function. Next he pointed out their 

 use in formiug sand-banks, which became highly beneficial as exten- 

 sive fields for the maintenance of various species of the finny tribes, as 

 in the great banks of Newfoundland. Next, this commingling of the 

 waters of several regions tended to change and renew from time to 

 time the soil of these banks, — which, like "manuring and working our 

 fields, was found to be necessary for preserving these extensive pas- 

 tures for the fish. Lastly, by bringing down from Polar r gions the 

 enormous masses of ice, which under the name of icebergs, were at 

 times found to be settiug down towards Tropical regions, they tend at 

 tlie same time to ameliorate the great heats of those regions, aud to 

 preveut the Polar legions from becoming blocked up with accumulat- 

 ing mountains of ice which, but for this provision, would soon be 

 oushed down as extensive glaciers, rendering whole tracts of our tem- 

 perate zones uninhabitable wilds. Dr. Scoresby concluded by point _ng 

 out several meteorological influences of these currents, by causing ex- 

 tensive fogs or winds more or less violent. 



' On Dynamical Sequences in Kdsmos,' by W. J. M. Watersox — 

 The Dynamic theory of Heat, if accepted as being inductively demon- 

 strated, seems to supply us with a valuable standard of physical causa- 

 tion that in the course of time must have an important influence on the 

 progress of science. That some such standard has hitherto been want- 

 ing, seems to be proved by the barren results of the most eminent 

 mathematicians, when directed to molecular physics, offering as they 

 do so great a contrast to the success achieved in the fields of Astrono- 

 my. In these reunions of the British Association, it may not perhaps 

 be considered out of place, or as an illegitimate course of inquiry, to 

 assume the theory as proven, and endeavour to realize, as far as our 

 lights at present extend, the conditions and the sequence of action, im- 

 plied by its existence as a general principle throughout nature. The 

 evidence that supports the theory equally supports many views of 

 natural phenomena that are obviously dependant upon it as corollaries, 

 and which ought therefore to be always associated With it. Among 

 these I would beg attention to a few that seem specially to demand 

 notice at the present stage of our progress. 1 —Equilibrium and Se- 

 quence of Temperature in relation to a centripetal force. — The dynamic 

 theory of heat requires that the law of vertical equilibrium of temp, rature 

 should be (liferent from the lam of horizontal equilibrium. In whatever 

 way conduction may be effected, equilibrium of temperature is by the 

 theory equilibrium of force : maintained by a constant in; srehange of 

 equal action or impulse between ac'j.vcent molecules, in a state of 

 activity. The interchange may take prace by direct contact or through 

 an intermedium affected by and capable of affecting the active stale 

 of the molecules. In either case, the vertically resolved portion of this 

 active state must be influenced by the centripetal force, of the planet 



which tends to increase a downward impulse and diminish an upward 

 impulse. Thus, the condition of motion once admitted, involves a 

 greater intensity at the lower aspect of a molecular orbit than at it* 

 upper, caused by the force of gravitation acting in the interval, which 

 must thus establish a gradient of increasing temperature towards the 

 centre, as the natural condition of a vertical equilibrium. An increas- 

 ing temperature below the surface of the earth being a recognized fact, 

 it is possible that the condition of permanent equilibrium in our pla- 

 net is already attained ; aud if in any mathematical speculations on the 

 interior condition of our globe, we assume that conduction takes place 

 the tame in all directions, vertical as well as horizontal, we shall cer- 

 tainly lie proceeding on a. false assumption if the theory is correct. A 

 vertical gradient of temperature in the atmosphere is another recog- 

 nized fact impossible to reconcile with any previous theory, but so 

 completely in accordance with these dynamic views, that if we merely 

 assume the molecules of air to be free elastic projectiles, we may 

 deduce its actual numerical value from the specific gravity of the com- 

 ponent gases. Prom this hypothesis, too, all the physical properties 

 of gases may be mathematically deduced. The relation that must 

 subsist between heat and gravitation is extremely interesting, and 

 deserves to be enlarged upon. It is in perfect conformity with the views 

 geuerally entertained of the progressive formation of the solar system 

 — the nebular hypothesis of La Place. The dynamical sequence may 

 be illustrated as follows. Suppose a 321b cannon ball to descend 

 through the earth's radius under ihe influence of the same force of 

 gravity as exists ou the surface, the velocity acquired is 36,700 feet per 

 second, or about seven miles. This is the same velocity as the ball 

 would acquire in descending from an infinite height to the surface of 

 the earth. Considering the Ball as an terolite encountering the atmos- 

 phere or earth's surface w T ith this velocity, we are now enabled to 

 compute the amount of heat generated by the concussion. 321b of 

 water falling through a height of about 673 feet obtains an increase of 

 1° by the concussion, 321b. of iron about 9°. The concussion due to 

 the velocity of seven miles per second would generate heat enough to 

 raise the temperature of the ball 280,000 degrees. In the same way, 

 it may be computed that if the ball descended to the surface of the 

 sun, it would acquire a velocity of 545 miles per second, and the heat 

 equivalent of the concussion is 1,800 million degrees. We may thus 

 obtain an idea of the vast evolution of heat that might be caused by 

 the process of central aggregation of matter under the influence of its 

 gravitating energy ; nor does it seem necessary to look further tor the 

 origin or continuance either of the solar heat or for that of the interior 

 of our planet. While gravitation thus generates heat centripetally, 

 radiation may be viewed as the escape of vis viva centrifugally. The 

 modes of central collocation and of dispersion are equally mysterious: 

 further than that, they appear as parts of a dynamical cycle. While a 

 body is falling towards the sun, vis viva is generated in certain points 

 of space, and conveyed to the centre by the body whose molecules 

 move together in the passage downwards. The shock at the centre 

 puts an end to this species of motion, but generates another apparently 

 of a vibratory kind in the molecular elements, which has the effect of 

 awakening a radiating power through space ; or what may be viewed 

 as a centrifugal transference of vis viva iutotheregions of space. While 

 this vis viva generated in space is inevitably carried to a centre before 

 it js thus re-issued, we have the residual phenomenon of a central 

 body augmented in mass by the process. The physical circle would 

 be complete if this central body had a motion through space which 

 brought it in contact with another; both, it may be, exhausted of their 

 central vis viva, the shock might he supposed capable of dispersing and 

 projecting the component part so far from the common centre of gravity 

 as to renew the original nebulous form. In M. Pouillet's researches 

 (Taylor's ' Sc.ieut. Mem.' vol. iv.) we have a striking view of the 

 extreme slowness of the process of radiation from the sun. Making 

 use of the same data, aud converting the equivalent of solar radiation 

 ifito quantity of matter of the density of water falling to the sun from 

 remote regions, we may see by a little calculation that the qautity re- 

 quired in one year would cover its whole surface to the depth of 146 

 feet. Thus, the sun may be supplied with heat by the mere descent 

 of matter as aerolites to its surface. When such bodies encounter our 

 atmosphere, we have experience of the dazzling appearances of igni- 

 tion or combustion manifested, and may judge of the effects pi a con- 

 tinued shower of such bodies sufficient to cover the surface to a sensi- 

 ble depth. Each meteor signals an accession to the earth's mass, and 

 brings also an accession of heat. If the united mass of all such me- 

 teors that impinge on our planet throughout cue year were made visible 

 to us as one aerolite descending at regular yearly intervals, there is 

 little doubt it would suggest to the mind of the most careless observer 

 the probability of the earth growing in size by such periodical contri- 

 butions. The geologist, accustomed to the consideration of vast periods 

 of time, might speculate on the possibility of it having thus materially 

 increased in dimensions while the abode of organic life, without in the 



