SECT. XVII. i. 5. OF MOTIONS. 145 



fubject, you ufe variety of mufcles in walking about your parlour, 

 or in fitting at your writing-table. 



5. Innumerable catenations of motions may proceed at the 

 fame time, without incommoding each other. Of thefe are 

 the motions of the heart and arteries ; thofe of digeition and 

 glandular fecretion ; of the ideas, or fenfual motions ; thofe of 

 progreflion, and of fpeaking *, the great annual circle of actions 

 fo apparent in birds in their times of breeding and moulting ; 

 the monthly circles of many female animals ; and the diurnal 

 circles of fleeping and waking, of fulaefs and inanition. 



6. Some links of fucceflive trains or of fynchronous tribes of 

 a&ion may be left out without disjoining the whole. Such are 

 our ufual trains of recollection : after having travelled through 

 an entertaining country, and viewed many delightful lawns, 

 rolling rivers, and echoing rocks ; in the recollection of our 

 journey we leave out the many diftricts, that we crofied, which 

 were marked with no peculiar pleafure. Such alfo are our com- 

 plex ideas, they are catenated tribes of ideas, which do not per- 

 fectly refemble their correfpondent perceptions, becaufe fome of 

 the parts are omitted. 



7. If an interrupted circle of actions is not entirely difievered, 

 it will continue to proceed confufedly, till it comes to the part 

 of the circle, where it was interrupted. 



The vital motions in a fever from drunkennefs, and in other 

 periodical difeafes, are inftances of this circum (lance. The ac- 

 cidental inebriate does not recover himfelf perfectly till about 

 the fame hour on the fucceeding day. The accuftomed drunk- 

 ard is difordered if he has not his ufual potation of ferment- 

 ed liquor. So if a confiderable part of a connected tribe of ac- 

 tion be difturbed, that whole tribe goes on with confufion, till 

 the part of the tribe affected regains its accuftomed catenations. 

 So vertigo produces vomiting, and a great fecretion of bile, as 

 in fea-ficknefs, all thefe being parts of the tribe of irritative cat- 

 enations. 



8. Weaker catenated trains may be diflevered by the fudden 

 exertion of the ftronger. When a child firft attempts to walk 

 acrofs a room, call to him, and he inftantly falls upon the ground. 

 So while I am thinking over the virtues of my friend, if the 

 tea-kettle fpurt out fome hot water on my flocking ; the fudden 

 pain breaks the weaker chain of ideas, and introduces a new 

 group of figures of its own This circumftance is extended to 

 fome unnatural trains of action, which have not been confirmed 

 by long habit ; as the hiccough, or an ague-fit, which are fre- 

 quently curable by furprife. A young lady about eleven years old 

 had for five days had a, contraction of one mufcle in her fore arm, 



VOL. I. U and 



