ASC 



ASC 



straight tubes. Some liquors, as spirit of 

 wine and oil of turpentine, ascend with 

 greater celerity than others ; and some 

 rise after a different manner from others. 

 Mercury does not ascend at all, but ra- 

 ther subsides. Upon the same principle, 

 two smooth polished plates of glass, me- 

 tal, stone, or other matter, being so dis- 

 posed as to be almost contiguous, have 

 the effect of several parallel capillary 

 tubes ; and the fluid rises in them ac- 

 cordingly : the like may be said of a ves- 

 sel filled with sand, &c. the divers little 

 interstices of which form as it were a kind 

 of capillary tubes : so that the same prin- 

 ciple accounts for the appearance in them 

 all. And to the same may probably be 

 ascribed the ascent of the sap in vegeta- 

 bles. Thus Sir I. Newton says, if a large 

 pipe of glass be filled with sifted ashes, 

 well pressed together, and one end 

 dipped into stagnant water, the fluid will 

 ascend slowly in the ashes, so as in the 

 space of a week or fortnight to reach the 

 height of 30 or 40 inches above the stag- 

 nant water. This ascent is wholly owing 

 to the action of those particles of the 

 ashes which are upon the surface of the 

 elevated water ; those within the water 

 attracting as much downwards as up- 

 wards : it follows, that the action of such 

 particles is very strong ; though, being 

 less dense and close than those ofthe glass, 

 their action is not equal to that of glass, 

 which keeps quicksilver suspended to 

 the height of 60 or 70 inches, and there- 

 fore acts with a force which would keep 

 water suspended to the height of about 

 60 feet By the same principle a sponge 

 sucks in water; and the glands in the bo- 

 dies of animals, according to their several 

 natures and dispositions, imbibe various 

 juices from the blood. If a drop of oil, 

 water, or other fluid, be laid on a glass 

 plane perpendicular to the horizon, so as 

 to stand without breaking or running off, 

 and another plane inclined to the former, 

 so as to meet at top, be brought to touch 

 the drop, then will the drop break, and 

 ascend towards the touching end of the 

 planes ; and it will ascend the faster in 

 proportion as it is higher, because the 

 distance between the planes is constantly 

 decreasing. After the same manner the 

 drop may be brought to any part ofthe 

 planes, either upward or downward, or 

 sideways, by altering the angle of inclina- 

 tion. Lastly, if the same perpendicular 

 planes be so placed as that two of their 

 sides meet, and form a small angle, the 

 other two only being kept apart by the 

 interposition of some thin body, and thus 

 immerged in a fluid tinged with some co- 



lour, the fluid will ascend between the 

 planes, and this the highest where the 

 planes are nearest, so as to form a curve 

 line which is found to be a just hyberpo- 

 la, one ofthe asymptotes whereof is the 

 line ofthe fluid, the other being a line 

 drawn along the touching sides. The 

 physical cause in all these phenomena is 

 the same power of attraction. 



ASCIDIA, in natural history, a genus 

 of worms, ofthe order Mollusca. Body 

 fixed, roundish, with two apertures, 

 generally placed near the upper end, one 

 beneath the other. There are more than 

 40 species found in the sea, adhering by 

 their base to rocks, shells, and other sub- 

 marine substances. They are more or 

 less gelatinous, and have the power of 

 squirting out the water which they take 

 in. Some of them are esculent, most of 

 them sessile, though a few are furnished 

 with a long stalk, or tubular stem. They 

 alternate lycontract and dilate themselves, 

 and are often found in great numbers ad- 

 hering to the bottoms of ships. 



ASCII, among geographers, an appel- 

 lation given to those inhabitants of the 

 earth, who, at certain seasons of the year, 

 have no shadow : such are all the inhabi- 

 tants ofthe torrid zone, when the sun is 

 vertical to them. 



ASCIUM, in botany, a genus ofthe Po- 

 lyandria Monogynia classand order. Cha- 

 racter : calyx five-leaved ; petals five ; 

 berry -four celled, with two seeds in each. 

 One species in Guiana, a tree 80 feet high. 



ASCLEPIAS, swallow-wort ,in botany, a 

 genus of the Pentandria Digynia class of 

 plants, the calyx of which is a permanent 

 perianthium. divided into five acute and 

 small segments : the corolla consists of a 

 single petal, divided into five deep seg- 

 ments at the mouth ; and its fruit consists 

 of two follicles or vaginae, containing a 

 great number of imbricated seeds, wing- 

 ed with down. There are about 40 spe- 

 cies. The swallow-worts are either shrubs 

 or tall upright perennial herbaceous 

 plants; milky and poisonous, or least 

 acrid. The flowers are borne on solitary 

 peduncles, several together in umbels, 

 and surrounded with a many leaved in- 

 volucre. They are very singular in their 

 structure. Flies, in searching for the ho- 

 ney in the nectary, are frequently caught 

 by the legs, and are not able to extricate 

 themselves. A. syriaca is a native of 

 North America, where the tender shoots 

 are eaten as we eat asparagus. The flow- 

 ers are so odoriferous as to make it very 

 agreeable to travel in the woods, especial- 

 ly in the evening. They make a sugar 

 of them in Canada, gathering them in the 



