1870.] BARKER — ON VITAL AND PHYSICAL FORCES. 429 



protuberance, a pair of these little bars was fastened to the head 

 at this point; and to neutralize the results of a general rise of 

 temperature over the whole body, a second pair, reversed in 

 direction, was attached to the leg or arm, so that if a like increase 

 of heat came to both, the electricity developed by one would be 

 neutralized by the other, and no ejBFect be produced upon the 

 needle unless only one was affected. By long practice it was 

 assertained that a state of mental torpor could be induced, lasting 

 for hours, in which the needle remained stationary. But let a 

 person knock at the door outside the room, or speak a single 

 word, even though the experimenter remained absolutely passive, 

 and the reception of the intelligence caused the needle to swing- 

 through 20 degrees.^^ In explanation of this production of beat, 

 the analogy of the muscle at once suggests itself. No conversion 

 of energy is complete ; and as the heat of muscular action repre- 

 sents force which has escaped conversion into motion, so the heat 

 evolved during the reception of an idea, is energy which has 

 escaped conversion into thought, from precisely the same cause. 

 Moreover, these experiments have shown that ideas which affect 

 the emotions, produce most heat in their reception ; " a few 

 minutes' recitation to one's self of emotional poetry, producing 

 more effect than several hours of deep thought." Hence it is 

 evident that the mechanism for the production of deep thought, 

 accomplishes this conversion of energy far more perfectly than 

 that which produces simply emotion. But we may take a step 

 further in this same direction. A muscle, precisely as the law of 

 correlation requires, develops less heat when doing work than 

 when it contracts without doing it. Suppose, now, that beside 

 the simple reception of an idea by the brain, the thought is 

 expressed outwardly by some muscular sign. The conversion now 

 takes two directions, and in addition to the production of thought, 

 a portion of the energy appears as nerve and muscle-power ; less, 

 therefore, should appear as heat, according to our law of correla- 

 tion. Dr. Lombard's experiments have shown that the amount 

 of heat developed by the recitation to one's self of emotional 

 poetry, was in every case less when that recitation was oral ; i e., 

 had a muscular expression. These results are in accordance with 

 the well-known fact that emotion often finds relief in physical 

 demonstrations ; thus diminishing the emotional energy by con- 

 verting it into muscular. Nor do these facts rest upon physical 

 evidence alone. Chemistry teaches that thought-force, like 

 YoL.Y. D* Ko.4. 



