.-sA

EVA

,)0

EUC

annual evaporation from the surface of the water amounted to3(3.78 inches. The proportion for every month was the fol-

lowing:

Inches.

January...

.1.50

February.

.1.77

March.

April.

Mav.

June.-..

Inches.

July.3.11

August.3.01

September .3.18

October .2.31

November .1.51

December.1.49

Mr. Dalton found the evaporation from the surface of the waterin one of the driest and hottest days of summer rather more than0.2 of an inch. If we believe Mr. Williams, the evaporation fromthe surface of land covered with trees and other vegetables is one-third greater than from the surface of water; but this has not beenconfirmed by other philosophers. From his experiments it ap-pears, that in Bradford in New England the evaporation, during1 772, amounted to 42.65 inches. But from the way that his ex-periments were conducted, the amount was probably too great.From an experiment of Dr. Watson , made on the 2d of June1779, after a month's drought, it appears, that the evaporationfrom*a square inch of a grass plot amounted to 1.2 grains in anhour, or 28.S grains in 24 hours, which is 0.061 of an inch, hianother experiment, after there had been no rain for a week, theheat of the earth being 110°, the evaporation was found almosttwice as great, or = 0.108 of an inch in the day. The mean ofIhese two experiments is 0.084 inches, amounting for the whole ofJune to 2 62 inches. If we suppose this to bear the same propor-tion to the whole year that the evaporation in Dr. Dobson’s expe-riments for June do to the annual evaporation, we shall obtain anannual evaporation, amounting to about 22 inches. This is muchsmaller than that obtained by Mr. Williams. But Dr. Watson ’s me-thod was not susceptible of precision. He collected the vapourraised on the inside of a drinking-glass; but it was impossiblethat the glass could condense much more than one-half of whatdid rise, or would have been raised in other circumstances. Butthen the experiments were made in the hottest part of the day,when much more vapour is raised than during any other part of it.

I he most exact set of experiments on the evaporation from theJ-artii was made by Mr. Dalton and Mr. Hoyle, during 1796, andthe two succeeding years. The method which they adopted wasthis: Ha ving got a cylindrical vessel of tinned iron, ten inches indiameter, and three feet deep, there were inserted into it twop'pes turned downwards for the water to run off into bottles : theone pipe was near the bottom of the vessel, the other was an inchfrom the top. The vessel was Idled up for a few inches with gra-i el and sand, and all the rest with good fresh soil. It was thenput into a hole in the ground, and the space around Idled up withearth, except on one side, for the convenience of putting bottlesto the two pipes; then some water was poured on to sadden theearth, and as much of it as would was suffered to run throughwithout notice, by which the earth might be considered as saturat-ed with water. For some weeks the soil was kept above the levelotthe upper pipe, but latterly it was constantly a little below it,which precluded any water running off through it. For the firstyear the soil at top was bare ; but for the two last years it was co-hered with grass the same as any green field. Tilings being thuscircumstanced, a regular register was kept of the quantity of rain-'' er that rail oft from the surface of the earth through the upperfc (whilst that took place,) and also of the quantity of thatt 1 ,; ,c V ,m k down through the three feet of earth, and ran outke°t i' ^' e ' 0VVCI pipe. A rain-gauge of the same diameter wasP close by to find the quantity of rain for any corresponding"?■. * j 10 weight of the water which ran through the pipes being

fd' si / rom the water in the rain-gauge, tiie remainder wasUMdered as the weight of the water evaporated from the earth in0 A, VPMcl * I he following table exhibits the mean annual result1 U'cse experiments:

Vol. n.— K0 .77.

Mean

Mean

Water through the two pipes.

Mean.

Ham.

Evap.

Inch.

Inch.

Inch.

1796.

1797.

1793.

Inch.

Inch.

Inch.

January

1.897-

.680 —

1.774+

1.450+

2.458

1.00S

February

1.778-

.918 —

1.122

1.273

1.801

.52S

March

.431-

.070—

.335

.279

.902

.623

April

.220-

.295-

.ISO

.232

1.717

1.4S5

May

2.027-

- 2.443+

.010

1.493+

4.177

2.634

June

.171-

- .726

—

.299

2.483

2.184

I u 1V

.153-

- .025

—

.059

4.154

4.095

August

—

—

.504

.163

3.554

3.386

September

--.

.976

-—

.325

3.279

2.954

October

—

.630

- .

.227

2.899

2.672

Novembet

—

1.044

1.594

.879

2.934

2.055

December

.200

3.077

1.878+

1.718+

3.202

1.484

6.S77—

10.934-

7.379

8.402

33.560

25.158

Rain

30.629-

38.791-

31.259

Evapor.

23.725 —

27.S57 —

23.862

From these experiments it appears that the quantity of vapourraised annually at Manc hester is about 25 inches. It to this weadd five inches for the dew with Mr. Dalton, it will make the an-nual evaporation 30 indies. Now, if we consider the situation ofEngland, and the greater quantity of vapour raised from water, itwill not surely be considered as too great an allowance if we esti-mate the mean annual evaporation over the whole surface of theglobe at 35 indies. But 33 inches from every square inch onthe superficies of the globe make 94,450 cubic miles, equal to thewater annually evaporated over the w hole globe. Was this pro-digious mass of water all to subsist in the atmosphere at once, itwould increase its mass by about a twelfth, and raise the barometernearly three inches. Bin this never happens; no day passes with-out rain in some part of the earth, so that part of the evaporatedwater is constantly precipitated again. Indeed it would be im-possible for the whole of the evaporated water to subsist in the at-mosphere at once, at least in the state of vapour.

EVASION, in law, any subtle endeavour to set aside truth, orto escape the punishment of the law. Thus, if a person says to an-other that he will not strike him, but will give him a pot of ale tostrike him first, and accordingly he strikes, the returning of it is'punishable; and if the person first striking be killed, it is murder:for no man shall evade the justice of the law by such a pretence tocover his malice.

EVATES, a branch of the Druids. Strabo divides the British and Gaulish philosophers into three sects; bards, evates, anddruids, lie adds, that the bards were the poets and musicians ;the evates, the priests and naturalists; and the druids, moralists aswell as naturalists: but Marcellus and Ilornius reduce them all totwo sects, viz. the Bards and Druids .

EVAUX, a town of France , in the department of Cretise, 18miles N. N. F. of Aulmsson.

F.UBAGKS, or EUBATES, an order of priests or philoso-phers among the ancient Celta: or Gauls : some suppose them tohe the same with the druids and saroniche of Diodorus ; and others,that they were the same w ith what Strabo calls Evates.

EUBCEA, or ABANTIUS, in ancient geography, an oblongisland, stretching out between Attica and Thessaly. It is now'called Negropont, from its principal town, anciently calledChalcis .

EUCALYPTUS, a genus of the Uexandria vnonogynia classand order. Calyx superior, permanent, truncate before iloweting,covered with an hemispherical deciduous lid ; corolla, none ; cap-sule four-celled, opening at top, inclosing many seeds. There aretwo species, lofty trees of New Holland ; called also the red-gumtree, from a gummy mutter, in which one of them, the rcsinifera,abounds.

EUCHARIST properly signifies giving thanks; the wordF.e ^reoifia literally importing thanksgiving; being formed of iv,good, and thanks. This sacrament was instituted by Christ

himself, and the participation of it is called communion. As to thematmer of celebrating the eucharist among the primitive Christians ,after the customary oblations w ere made, the deacon brought water4 Q to