CLASS IV. 2. 2. 4. OF ASSOCIATION. 431 



especially if preceded by venesection and a brisk cathartic; but if 

 the offending tooth can be detected, the most certain cure is its 

 extraction. These partial head-achs are also liable to return at 

 the greater lunar periods, as about once a month. Five drops 

 from a two ounce phial of a saturated solution of arsenic twice 

 a day for a week or two have been said to prevent the returns of 

 this disease. See a Treatise on Arsenic by Dr. Fowler, of York. 

 Strong errhines have also been recommended. 



4. Epilepsies dol orifices periodus. Class III. 1. 1.8. The pain 

 which induces after about an hour the violent convulsions or in- 

 sanity, which constitute the painful epilepsy, generally observe 

 solar diurnal periods for four or five weeks, and are probably 

 governed by solar and lunar times in respect to their greater pe- 

 riods; for I have observed that the daily paroxysms, unless dis- 

 turbed by large doses of opium, recur at very nearly the same 

 hour, and after a few weeks the patients have recovered to re- 

 lapse again at the interval of a few months. But more obser- 

 vations are wanted upon this subject, which might be of great 

 advantage in preventing the attacks of this disease; as much less 

 opium given an hour before its expected daily return will pre- 

 vent the paroxysm, than is necessary to cure it, after it has com- 

 menced. 



5. Convulsionis dolorificae periodus. Class III. 1. 1. 6. The 

 pains, which produce these convulsions, are generally left after 

 rheumatism, and come on when the patients are become warm 

 in bed, or have been for a short time asleep, and are therefore 

 perhaps rather to be ascribed to the increasing sensibility of the 

 system during sleep, than to solar diurnal periods, as in Species 

 first and second of this Genus. 



6. Tussis periodicoe periodus. Periodic cough, Class IV. 2. 1. 

 9. returns at exact solar periods; that described in Sect.XXXVI. 

 3. 9. recurred about seven in the afternoon for several weeks, 

 till its periods were disturbed by opium, and then it recurred at 

 eleven at. night for about a week, and was then totally destroyed 

 by opium given in very large quantities, after having been pre- 

 viously for a few days omitted. 



7. Calamenm periodus. Periods of menstruation. The cor- 

 respondence of the periods of the catamenia with those of the 

 moon was treated of in Sect. XXXII. G. and can admit of no 

 more doubt, than that the returns of the tides are governed by 

 lunar influence. But the manner in which this is produced, b 

 less evident; it has commonly been ascribed to some effect of 

 the lunar gravitation on the circulating blood, as mentioned in 

 Sect. XXXII. 6. But it is more analogous to other animal 

 phenomena to suppose that the lunar gravitation immediately 



