A S C 



A S C 



Rad. 

 To t. lat. P'rO=5l° 32' 

 Ast. dccl. A ©=23° 28' 



To nnc afc. dif. tA = 33° 7' 



:= 1 0.000000 



10.099913 



9.63761 I 



9-737524 



This afceiifional difFerencc, 33° 7', converted into timf, 

 gives z"* 12' 28" for the time which the run rifes before, 

 and fets after the hour of fix, on the loiigeil day. Hence 

 it appears, that wlien the hititude and dechnation have the 

 fame name, the fun rifes before, and fets after I'lX ; but when 

 they are of contrary names, tlie fun rifes after, and fets be- 

 fore fix. And as the fun d^fcribes the parallel of declination 

 «m in 24 hours, being at « when it is noon, and at m when 

 it is midnight, the time in pafii.ig from m to ©, or the time of 

 rifing being doubled, gives the length of the night; and the 

 time of fetting being doubled gives the length of the day. 

 Confcquenily, 6''+2'" 12' 28"=8'' 12' 28", will be the time 

 of fetting, and 6 "- 2'' 12' 2S" = 3'' 47' 32", will be the time 

 of rifing; and 8'' 1 2' 28 "x2 = i6'' 24' 56" the length of 

 the day, and 3" 47' 32" x 2 = 7" 35' 4" the length of the 

 night. 



But when it is the (liorteft day at London, that is, wlieu 

 the fun has 23'^ 28' fouth declination, tlie lengths of the 

 day and night will change places; the day being 7" 35' 4", 

 and the night 16*' 24' 56". 



When the latitude and declination have the fame name, 

 the difference between the right afceitfion and the aiccnfional 

 difference, is the oblique afctnfion ; and their fum is the ob- 

 lique defcenfion; but when they are of contrary names, the 

 fum is the obhque afcenfion, and the difference is the oblique 

 defcenfion. 



The above folution is applicable to a flar, as well as to 

 the fun ; but on account of the fmall change in the declina- 

 tion of the ftars, the fame flar in any latitude may be con- 

 fidered as having the fame afcenfional diS'erence through the 

 year. Hence it appears, that the diurnal difference of the 

 fame liar's rifing, culminating, and fetting in the fame lati- 

 tude, is nearly equal to the diurnal difference of the fun's 

 right afcenfion. As the fun's mean apparent daily motion 

 is 59' 8" nearly, or in time 3' 56" 32'", tliis will be the 

 daily difference in the rifing, fouthing, and fetting of any 

 fixed ftar in the fame latitude. 



ASCENSIONIS, in Ichthyology, a fpecies of Perca 

 that inhabits the fea about Afcenfion idand; it is reddifli 

 above, whitifli beneath, and the tail is bifurcated. Olb. It. 

 p. 388. 



ASCENSORIUM fometimes occurs, in our ancient 

 writers, for a flair or itep. 



ASCENT, in a general fenfe, the motion of a body 

 tending upwards; or the continual recefs of a body from 

 the earth. In this fcnfe the word Hands oppofed to iLJccnt. 



The Peripatetics attribute the fpontaneous afcent of 

 bodies, to a principle of levity inherent in them. The 

 moderns deny any fuch thing as fpontaneous levity, and 

 (hew, that whatever alcends, does it in virtue of fome exter- 

 nal irapulfe or extnifion. Thus it is that fmokc, and other 

 rare bodies, ifcend in the atmofpherc; and oil, light woods, 

 &c. in water: not by any internal principle of levity, but 

 by the fupcrior gravity, or tendency downwards of the 

 parts of the medium in which they are. 



The afcent of light bodies in heavy mediums is produced 

 after the fame manner as the afcent of the hoiitci fcale of a 



balance It is not that Inch fcale has an internal principle 



by which it immediately tends upwards; but it is impelled up- 

 wards by the prcponderancy of the other fcule, the excefs 

 ol the weight of the one having the fame effect by augment- 



ing its impetus downwards, as fo much real levity in the 

 other; becaufc the tendencies mutually oppafe each other, 

 and that adion and re-adtion are always equal. See this 

 farther illuflrated under the articles Specific Gravity ^ and 

 Fluid. 



Ascent of Bodies on inclined Planes. See its doiflrine 

 and laws, under Inclined Plane. 



Ascent of Fluids, is particularly underftood of their 

 rifing above their own level, between the furfaces of nearly 

 contiguous bodies, or in flender capillary glafs tubes, or in 

 veffels filled with fand, aflies, or the like porous fubflances. 

 This cfFcdl happens as well in vacuo, as in the open air, 

 and in crooked as well as llraight tubes. Some liquors, as 

 fpirit of vrine, and oil of turpentine, afcend with greater 

 celerity than others ; and fome rife after a different man- 

 ner from others. Mercury does not afcend at all, but 

 rather fubfides. The phenomenon, with its caufes, Sic. 

 in the inflance of capillary tubes, will be fpukcn of more 

 at large under Capillary Tul/e. Upon the fame principle, 

 two fmootb poliflied plated of glafs, metal, flone, or other 

 matter, being fo difpofed as to be alnioft contiguous, have 

 the effect of feveral parallel capiliai-y tubes; and the fluid rifes 

 in them accordingly : the like may be faid of a vtffel filled 

 with fainl. Sec. the divers little interflices of which form as 

 it were a kind of capillary tubes. So that the fame prin- 

 ciple accounts for the appearance in them all. And to the 

 fame may probably be afcribed the afcent of the fap in 

 Vegetables. Thus Sir I. Newton.—-" If a large pipe of 

 glafi be filled with fifted allies, well preffed together, and 

 one end dipped into flagnant water, the fluid will afcend 

 (lowly in the allies, fo as in the fpace of a week or fortnight 

 to reach the height of thirty or forty inches above the flag- 

 nant water. This afcent is wholly owing to the aftion of 

 thofe particles of the afhes which are upon the furface of 

 the elevated water; thofe within the water attradling as 

 much downwards as upwards : it follows that the adlion of 

 fuch particles is veiy flrong ; though being lefs denfe and 

 clofe than thofe of the glals, their aftion is not equal to 

 that of glafs, which keeps quickjllver fufpended to the 

 height of fixty or feventy inches, and therefore atts with a 

 force which would keep water fufpended to the height of 

 about fixty feet. By the fame principle, a fponge fucks 

 in water; and the glands in the bodies of animals, accord- 

 ing to their feveral natures and difpofitions, imbibe various 

 juices fiom the blood." Optics, p. 367. 



If a drop of oil, water, or other fluid, be laid on a glafs 

 plane, perpendicular to the horizon, fo as to (land v.ithout 

 breaking, or running off; and another plane inclined to the 

 former fo as to meet a-top, be brought to touch the drop, 

 tlien will the drop break, and afcend towards the touching 

 end of the planes ; and it will afcend the fafler in proportion 

 as it is higher, becaufe the diftance between the planes is 

 conllantly decreafing. After the fame manner, the drop may 

 be brouglit to any part of tiie planes, either upward, or down- 

 ward, or fideways, by altering the angle of inchnation. 

 L,alliy, if the fame perpendicular planes be fo placed, as that 

 two of their fides meet, and form a fmall angle, the otiier 

 two only being kept apart by the intei-pofitlon of fome 

 thin body ; and thus immcrged in a fluid tinged with fome 

 colour; the fluid will afcend between the planes, and this 

 the hii^heft where the planes are ncarell ; fo as to form a 

 curve line, which is found to be a jull hyperbola, one of the 

 afymptotes whereof is the liiie of the fluid, the other being 

 a line drawn along the touching fides. The phyfical caufe, 

 in all thefe pli-.uiiomena, is the fame power of attiaClioa. 

 See Hydrostatics (P/. I. fs- 1.), and Cohesion. 



Ascent 



