Sect. XXXII. 7. i. OF IRRITATION. 29 r 



month with great exaftnefs in healthy patients (and perhaps the 

 venereal orgafm in brute animals does the fame), yet thefe pe- 

 riods do not commence either at the fyzygies or quadratures of 

 the lunations, but at whatever time of the lunar periods they be- 

 gin, they obferve the fame in their returns till fome greater 

 caufe difturbs them. 



Hence, though the belt way to calculate the time of the ex- 

 pected returns of the paroxyfms of periodical difeafes is to count 

 the number of hours between the commencement of the two 

 preceding fits, yet the following obfervations may be worth at- 

 tending to, when we endeavour to prevent the returns of maniac- 

 al or epileptic difeafes ; whofe periods (at the beginning of them 

 efpecially) frequently obferve the fyzygies of the moon and fun, 

 and particularly about the equinox. 



The greateft of the two tides happening in every revolution 

 of the moon, is that when the moon approaches neareft to the 

 zenith or nadir; for this reafon, while the fun is in the northern 

 figns, that is during the vernal and fummer months, the greater 

 of the two diurnal tides in our latitude is that, when the moon 

 is above the horizon ; and when the fun is in the fouthern figns, 

 or during the autumnal and winter months, the greater tide is 

 that, which arifes when the moon is below the horizon ; and 

 as the fun approaches fome what nearer the earth in winter than 

 in fummer, the greateft equinoctial tides are obferved to be a lit- 

 tle before the vernal equinox, and a little after the autumnal one. 



Do not the cold periods of lunar difeafes commence a few 

 hours before the fouthing of the moon during the vernal and 

 fummer months, and before the northing of the moon during 

 the autumnal and winter months ? Do not paifies and apoplex- 

 ies, which occur about the equinoxes, happen a few days before 

 the vernal equinoctial lunation, and after the autumnal one ? 

 Are not the periods of thofe diurnal difeafes more obftinate, 

 that commence many hours before the fouthing or northing of 

 •the moon, than of thofe which commence at thofe times ? Are 

 not thofe paifies and apoplexies more dangerous which com- 

 mence many days before the fyzygies of the moon, than thofe 

 which happen at thofe times ? See Sec~t. XXXVI. on the peri- 

 ods of difeafes. 



VII. Another very frequent caufe of the cold fit of fever is 

 the quiefcence of fome of thofe large congeries of glands, which 

 compofe the liver, fpleen, or pancreas ; one or more of which 

 are frequently fo enlarged in the autumnal intermittents as to 

 be perceptible to the touch externally, and are called by the vul- 

 gar ague-cakes. As thefe glands are ftimulated into action by 

 the fpecific pungency of the fluids, which they abforb, the gener- 

 al 



