LESSONS IN GREEK. 



of supposing that it in the thaw which burnt* thorn. The real 

 fact in th.it tln< ioo ho* done it, hut it it-main* an a solid j.iutf 

 till tlio thaw com*-*, it thru becomes inoltod, and the water at 

 onoe flowa out of the crack. 



Tho ouiiHtruction of thermometer* U ckmoly connected with 



this Hul.ji-.-t , I. MI it h:is boon alroady described in our Lessons 



Vol. 11. page 77, and wo therefore refer the ntu- 



dont to tlu> account given there. The Fahrenheit scale u that 



UBod in those lessons. 



Tho expansion of gases ia much greater than that of either 

 : liquids, being usually token at jji ' * no volume at 

 :>^' for r;i.-!i ' n-fo they are raised above that point. This 

 rate is very nearly the same for all gases, and is uniform for all 

 temperature*, uxcopt the gas bo near its point of condensation. 

 < is taken of the groat expansibility of air in the 

 i of the differential thermometer, which is nnod to 

 measure very small amounts of heat. It consists of two largo 

 hull's (Fig. 12) containing air, and connected by a tube, in which 

 d a drop of coloured liquid to servo as an index. If 

 now one of the bulbs be raised to a higher temperature than the 

 other, the air in it will expand and drive the liquid nearer the 

 other, tho distance it moves being shown by means of a gradu- 

 ated scale. When both bulbs are exposed to tho same tempera- 

 ture no effect is produced ; it is only the difference that is shown, 

 and hciio- its name is derived. 



The next effect of heat we have to notice is that manifested 

 in producing a change of state in different bodies. The three 

 states of water ice, water, steam familiar to all, arise merely 

 from alterations in the heat. Some substances do not fuse at 

 all, but at high temperatures become decomposed; most organic 

 substances belong to this class. Many bodies, however, fuse at 

 moderate degrees of temperature, and we find the following laws 

 respecting the point of fusion : Tho temperature at which fusion 

 commences is constant for any substance so long as the pressure 

 remains constant ; and, from tho time that fusion commences, the 

 temperature remains stationary until the whole of the substance 

 is melted. Some substances, as iron and wax, soften gradually 

 before they actually fuse, while others, as lead and copper, melt 

 without this softening. In tho case of iron, great advantage is 

 derived from this property, as by means of it tho blacksmith 

 can weld different pieces together, or mould them to shape on 

 his anvil. This cannot be done with those metals which do not 

 soften in this way. 



From the fact mentioned above, that tho temperature of any 

 body ceases to rise as long as it is melting, even though the 

 source of heat is still applied to it, we see at once that much 

 heat must disappear in the process. This is said to become 

 latent. Further illustration of this fact is easily obtained. 

 Take equal weights of water at 32" and at 174, and mix them 

 together ; the temperature of the mixture will bo the mean of 

 tho two, or 103. Now take the same weight of ice at 32 and 

 water at 174, and mix as before, and tho temperature will be 

 found to be only 32 instead of 103; all the ice, however, will 

 be melted. Tho 141 of heat has, then, evidently been con- 

 sumed in melting the ice. 



LESSONS IN GREEK. XL. 



LIQUID VEEBS. 

 THE FORMATION OF THE TENSES OF LIQUID VERBS. 



LIQUID VERBS aro those whose characteristic is a liquid 

 namely, \, u, v, or p. Liquid verbs form the future active and 

 middle and tho first aorist active and middle without tho tense- 

 characteristic <r, and yet take tho tense-characteristic /c in the 

 first perfect and pluperfect active ; as 



ff<t>a\\a (pure stem 2*AA), I trip up, stumble ; 



oi, fut. <r<pa\-&, aor. 1 -<r<prjA-a, perf. t-<r<pa\-Ka. 



Tho future terminations of liquid verbs, , ovfj.cu (from f<rw, 

 ecrojuai), are circumfloxed like tho present active and middle of 

 contracted verbs in o>, as <pi\-ta, <pi\-ov/j.au. Liquid verbs havo 

 not the third future. 



With few exceptions, the present of those verbs whoso stem- 

 vowel is short, has undergone a strengthening of the pure stem, 

 which strengthening consists either in tho doubling of the A, 

 or the liquid v is introduce I after the characteristic : as ffp*\\u, 

 stem 24AA, present <r^oA \.u, tho A. being doubled , Tffu>-u>, pure 



stem TEM, v being introduced to form the present : or in thin, 

 that the root-rowel U either lengthened namely, I is lengthened 

 into I and into 0, as all verb* in in, few for example, xpiw, 

 I judge; euii/rt*, I u-ar-i off; <ri>p<*, I draw out, pore item* KPIN 

 (I), AMTN (0), 2TP (6) : or the rowel U changed into a diph- 

 thong that in, a into at, into for example, ^xu^-w, / haw\ 

 KTttv.u, I kill ; pure atom 4>AN, KTEN. M*-, / irmain. Mid 

 cM-", / divide, retain the form of the pore atom ; for example :-* 

 ruxs arena. rue* rim. ALTKIUTIOV. 



2+AA, (r^oA-A-w, X doubled. 



TEM, Ttp'V-v, v introduced. 



KPIN, tcplir-w, I lengthened. 



AMTN, auOr-w, 6 lengthened. 



2TP, ffdp-tt, 6 lengthened. 



AN, <pa-cK-o>, a changed into at. 



KTEN KTt-t-v-w, changed into . 



The strengthened (impure) stems thus formed remain only 

 in the present and the imperfect ; the other tenses are formed 

 from the pore stem, the short rowel being lengthened by the 

 change of 7 into I, V into 0, a into r), t into <i in the first aorist 

 active and middle ; thus 



PURE STEM. PRESET!. FUTURE. AOR. 1 ACT. AOR. 1 MID. 



S'frAA, (npoAAu), fffpdXu, t-ffiptj\-a, -<T(^)A-afii)r. 



The first perfect active is e-<r<j>oA-*ca, and the second aorist 

 passive is t-ff<pa\-i)r. The future active always bears a circum- 

 flex accent crrtAcS, and the future middle ends in oifuu. 



Liquid verbs with monosyllabic atoms and tho stem-vowel 

 take the conversion a in the second aorist, in the first perfect 

 and pluperfect active, the perfect and pluperfect middle or 

 passive, in the first aorist, first and second future passive, as 

 well as in the verbal adjective ; and the conversion o in the 

 second perfect and pluperfect as in (rrtAAw, / send. 

 ffrt\\-<a, fut. ffTf A-, perf. 1 act. <-<rraA-jta, perf. mid. or pass. 



f-ffTa\-(j.cu, aor. 1 pass. t-(na\-drn> (poet.), aor. 2 pass. 



e-flroA-iji', verbal adj. <rroA-Tto$. 

 <p8ftp-ti>, fut. <(>Ofp-, perf. 1 act. (-(pOap-Ka., perf. mid. or pass. 



t-<p9ap-ij.au, aor. 2 pass. t-<pOap-ijy, verbal adj. Qdap-ros, but" 



perf. 2 t-ipOop-a. 



Verbs of more than one syllable are not capable of con- 

 version, as ayyf AAo>, / announce, i)yy(\Ktt, rry-yt\fj.cu, ijy-yf\8i)t>. 



The following verbs lengthen the short vowel of the stem 

 irregularly, those in a.ivu> changing cu not into ij, but d ; as 

 iff\va.iv<a, I make lean, urgi'dyo, iffx.va.vcu ; KtpSatw, I gain, ttctp- 

 Sava, KfpSavau ; KoiAaii/o), I hollow, cKoiAdca, xoiAdvai ; \(VKO.IVW, 

 I make white, opyaivu, I make angry, irtircuvca, I make ripe ; also 

 by all in pcupw, as irtpcuiKo, I finish, fut. -rtpavw, aor. crtpava, 

 inf. irepdvai ; and by all in tatvta, as iruuvta, / make fat, txidva, 

 iridcat (except juiaicco, I spot, /uifjvoi). Also cupu, I take, and 

 aAAo/iat, I leap, belong here, rtpa, apcu, ^Aa^iiji', aXao-dat (not 

 fjpai, r;\a<r0ai). 



The first perfect active of verbs with the characteristic v 

 must end in yica., as /xe-^iay-Ka (from niaivu), instead of /- 

 HIOLV-KO.. This form, however, is found only among the later 

 writers. There are also other forms, as KipSaiyta, I gain, perf. 

 KfKfpSajca ; fjitvu, I remain, /IC^CJ/TJKO, from MENEXJ. Many 

 verbs have no perfect. Also the verbs with M for their cha- 

 racteristic form the perfect from a theme in , as vt^-w, I divide, 

 txvtfjLriKa, as from NEMEfl. 



The three verbs following, with v for their characteristic, 

 eject the v in not only the perfect and pluperfect active, but 

 also in tho perfect and pluperfect middle or passive, in the first 

 aorist passive, and in the verbal adjective : 



xpivtii, I separate, xocpiKO, Kticplfuu, cicpt^r. 



K\ivca, I bend, KKAJK<I, K? KAiucu, e*cA0jr. 



K\vv<a, I wash, irtrACKO, tAO/u, tirAi/Srjr. 



Bespecting the formation of the perfect middle or passive, 

 observe tho following : 



When <rO would follow a liquid, the <r is thrown out, as 

 7777eA<r0cw, rryyf \-Oai ; so vt<pav6tii. 



In verbs in cuvta and \>v<a the v before the termination begin- 

 ning with /* commonly disappears, and a a is introduced to 

 strengthen tho syllable ; as <f>aiv-w, vttfta.-a--fi.au, v<$a-<r-/i<0a ; 

 but in some verbs of this kind tho v assimilates itself to the 

 following u, as irapo^vvtt, I sharpen, excite, fapv^vu-fuu, inf. 

 Oai ; aiffxvfta, I cause- shame, i) a x*> !*-/**", rnf . pcrx''-Pai- 



In tho second perfect which, however, is formed by only t 



