T H I 



375 



T H I 



hard or salted food excites great thirst, probably because 

 a large quantity of fluid is abstracted from the blood for 

 its digestion ; but fruits and soft vegetables assist, by the 

 quantity of water which they contain, in quenching thirst ; 

 and infants, receiving their food and drink at once from 

 the milk which is naturally provided for them, are perhaps 

 not sensible of thirst as a healthy sensation different from 

 that of hunger. Strong drinks, again, excite thirst, but in 

 a peculiar manner ; either by their irritation of the nerves 

 of the digestive canal, or by the great quantity of fluid 

 which, by exosmosis, they withdraw from the blood. 



As a general rule, the degree of thirst during health is 

 directly proportioned to the rapidity of the exhalation of 

 fluid from the skin and lungs. Hence the naturally greater 

 thirst in summer, and the desire for the fresh fruits of the 

 season, which both supply water and produce moisture of 

 the mouth by exciting a flow of saliva ; hence also the 

 less natural thirst which is produced by remaining in hot 

 and crowded rooms, arid that which is so painfully felt by 

 who work about iron-forges and steam-engines, and 

 which they can satisfy only by frequent and enormous 

 draughts of water. Of the same kind is the thirst which 

 many have felt in ascending high mountains, on which, as 

 the atmospheric pressure diminishes, the evaporation from 

 the skin is increased ; and that which is produced by ex- 

 posure to a dry brisk wind. 



The sensations and other circumstances accompanying 

 ordinary thirst need not be described. The sensation 

 of dryness of the mouth and throat, which most strongly 

 characterizes it, is not always the result of those parts 

 being really deficient in moisture, nor is it removed by 

 supplying the mouth alone with fluid. It is an example 

 cif that class of local sensations which are indicative 

 of peculiar general conditions of the body, or of the 

 state of some other part in which no sensation is per- 

 il. These have been called reflex sensations; and 

 one of the characters common to many of them, as well as 

 to thirst, is that the animal perceiving them is impelled to 

 actions which tend to the health of the body. For 

 example, the irritation which is felt at the upper part of 

 the throat, and which induces one to cough, is often due, 

 not to a direct excitement of that part, but to the existence 

 of some irritating substance, such as mucus, in a distant 

 and insensible part of the air-passages. From the latter 

 part an impression is conveyed to the nervous centre ; 

 thence, without directly giving rise to a sensation, it is 

 supposed to be reflected to the sensitive nerves of the 

 glottis; and the sensation which is perceived through these 

 excites the desire to cough, and thus leads to the expul- I 

 sion of the irritating substance. In like manner the sen- 

 sation of dryness in the mouth induces one to drink, and 

 so to remove not merely the sensation, but the more im- 

 portant condition, such as a deficiency of water in the 

 blood, of which it is a SIL'H. 



But as cough may be produced by a direct irritation of 

 the upper part of the larynx, so a sensation similar to that 

 of thirst is often due only to a rapid evaporation from the 

 mouth and throat, as in long speaking or singing ; but this 

 may be removed by merely washing the mouth and throat, 

 or by exciting a flow of saliva ; means which are insuffi- 

 cient for the remedy of real thirst. That the introduction 

 of water into the blood is necessary for quenching thirst 

 has been often proved in persons who in attempting suicide 

 have divided the pharynx or oesophagus, so that they could 

 no longer swallow in the ordinary mode. Repeated wash- 

 ing of the mouth has been altogether unavailing to relieve 

 their thirst; but the injecting of water through the wound 

 into the stomach has quickly removed the sensation of 

 dryness in the mouth, though none of the water passed 

 through it. Similar facts have been observed in those \\ ho,- 

 being unable to swallow or to have liquids forced into their 

 stomachs, have been long immersed in baths, and in ship- 

 wrecked sailors who have had no fresh water and have re- 

 lieved their thirst by keeping their clothes soaked with sea- 

 water. 



The thirst of many diseases, such as acute fevers and 

 important inflammations, affords another proof of the sen- 

 sation peculiar to it. being chiefly a sitrn of some general 

 condition ; for in these the sensation often continues not 

 only when the mouth is moist, but after large quantities 

 of water have been imbibed, being here probably depend- 

 ent on some condition of the blood which dilution does 



not remedy. In certain cases also the sensation seems to 

 be entirely subjective, and dependent on a peculiar condi- 

 tion of the nervous system. This is remarkably the case 

 in a disease of which the true pathology is unknown, and 

 which has been named polydipsia, from its chief symp- 

 tom being an excessive and insatiable thirst. Several ex- 

 amples have been recorded, in some of which the thirst 

 probably depended on a constant discharge of fluids from 

 diabetic Blood, or by dropsical effusions, or otherwise : but 

 in many it could not be traced to such an origin. One of 

 the most remarkable of them is described by Mr. Ware, in 

 the ' London Medical and Physical Journal ' for 1816 : the 

 patient was a man 22 years old, whose health was in other 

 respects good, but who was compelled to drink six gallons 

 of water daily. He had been accustomed to drink nearly 

 as much from his childhood ; and, if deprived of a suffi- 

 cient supply, his head was always affected, and fainting 

 and dullness of the senses ensued. Nearly all the cases of 

 the same kind which have been published are collected 

 in a paper by M. Lacombe, in the French medical jour- 

 nal 'L'Experience,' for May and June, 1841, and re- 

 ferences to several are given by Tiedemann, in his ' Physio- 

 logic des Menschen,' Band iii., p. 71. 



If thirst be long unallayed, it produces one of the most 

 dreadful states which a man can be compelled to bear. 

 Those who have attempted suicide by starvation have been 

 unable to resist the desire to drink, though they have en- 

 dured many days of abstinence from food, and have been 

 compelled thus for a time to protract their lives. The 

 same tortures have been endured by sailors wrecked far 

 from land. As the thirst increases, the mouth and throat 

 become painful and burning hot, the respiration grows 

 difficult, and the expired air feels hot and dry. The voice 

 becomes hoarse, the speech thick and indistinct, and the 

 pulse small and rapid. All secretion diminishes or is sup- 

 pressed, the skin is hot and dry, and the eyes become 

 painful and inflamed. The sensibility of every part of the 

 body seems exalted, at the same time that the power of the 

 muscles fails ; the mind passes slowly from restlessness and 

 anxiety to despair, and at last, as the body grows weaker, 

 begins to wander in a low delirium. At the close of life 

 there is an utter prostration of strength, and, in general, 

 insensibility ; but the inflammation of the mouth and eyes, 

 and of all the parts that are not projected from the air by 

 a thick cuticle, increases, and proceeds sometimes to gan- 

 grene. The time during which so miserable a state can be 

 endured varies with the strength of the sufferer. Haller 

 ; Eli-nx'iiln I'hiiaioliiffiee, t. vi.) has collected examples of 

 men who lived for at least fifteen days without drinking ; 

 but the more ordinary period is eight or ten days. 



THIRTY TYRANTS (of Athens). In the year 404 B.C., 

 when, after the Peloponnesian war, Athens had fallen into 

 the hands of Sparta through the treacherous designs of 

 the oligarchical party, the Spartans themselves did not 

 interfere in any direct way with the political constitution 

 of Athens (Diodorns, xiv. 4), but their negotiations with 

 Theramenes and others of the same party had convinced 

 them that even without their interference the democracy 

 would soon be abolished. In this expectation they were 

 not disappointed, as this was really the object of the oli- 

 garchical party. But as this party did not sufficiently trust 

 its own power, Lysander, who had already sailed to Samos, 

 was invited to attend the Assembly at Athens, in which 

 the question of reforming the constitution was to be con- 

 sidered. The presence of Lysander and other Spartan 

 generals with their armies, and the threats that were 

 uttered, silenced all opposition on the side of the popular 

 party, and on the proposition of Theramenes a decree was 

 .I that thirty men should be elected to draw up a new 

 iHition. (Xenophon, Hellen., ii. 3,2.) Lysias (in 

 A'/w/</7i., p. 126, ed. Steph.) gives a more satisfactory 

 account of the proceedings on that memorable day than 

 Xenophon. These thirty individuals were invested with the 

 sovereign power of the republic. Theramenes himself nomi- 

 ten, the Athenian ephors ten others, and the election 

 of the remaining ten was left to the people. The names of 

 the Thirty are preserved in Xenophon (Hi'llfn., ii. 3, 2). 

 Their government, a real reign of terror, which fortunately 

 did not last more than one year, was called in Athenian 

 history the year of anarchy, or the reign of the Thirty 

 Tyrants. From the moment that they had thus acquired an 

 apparently legal power, they filled the vacancies in the 



