140 



PROCEEDINGS OP THE AMERICAN ACADEMY 



TABLE XXV. — Synopsis of Methods for Obtaining the Mechanical 

 Equivalent of Heat. 



f a. Expansion or compression ac- 



I cording to tuliabatic curve. 



b. Expansion or compression ac- 

 cording to isothermal curve. 



1 Reversible Process \ c ' Ex P ansiou or compression ac- 

 cording to auy curve with re- 

 generator. 

 d. Electro magnetic engine driven 

 by thermo-electric pile in a cir- 

 cuit of no resistance. 



a. Friction, percus.-ion, etc. 



b. Heat from magneto-electric cur- 

 rents, or electric machine. 



( a. licit ' Mechanical Energy 

 a. Heat ^ Qravi{ation •• 



2. Irreversible Process 



/3. Ileat, Electric Energy 



I y. Ileat, Magnetic Energy , 



'{ 



I a Thermo-electric currents 

 f 1. Reversible Process { b. Pyro-eleetric pheuomeua (Preb- 

 le ably). 



( a. Heating of wire by current, or 

 [ 2. Irreversible Process \ heat produced by discharge of 



( electric battery. 



a. Thermo-electric current magnet- 

 1. Reversible Process \ izing a magnet in a circuit of 



no resistance. 



^IrreversibleProcessj- 11 ^,^-^ "*« d - 



pq 



% (a. Mechanical Energy. 



| 6 Electrical " 

 Radiant Energy, Ileat . . J ., 



(Radiant energy absorbed | c - Magnetic 

 by blackened surface.) (^ rf. Gravitation " 



( a Mechanical Energy 



|3. Chemical Energy, Heat 

 (Combustion, etc.) 



b. Electrical 



c. Magnetic 



d. Gravitation 



. Capillary energy, Heat . 

 (Heat produced when a liq- j c 

 uid is absorbed by a po- (^ d, 

 rous solid ) 



11 



Electrical energy, Heat 

 (Heat generated in a wire by I. c 

 an electrical current ) 



Mechanical Energy. 



Electrical " 



Magnetic " 

 Gravitation " 



Mechanical Energy 



Magnetic " 



Gravitation " 



o. Mechanical Energy 



Crooke's radiometer. 

 Thermo-electric pile. 

 Thermo-electric pile with electro- 

 magnet in circuit. 



1. Cannon. 



2. Electro-magnetic machine run by 



galv battery- 

 Current from battery. 

 Electro-magnet magnetized by a 



battery current. 



Movement of liquid by capillarity. 

 Electrical currents from capillary 

 action at surface of mercury. 



Raising of liquid by capillarity. 



Magneto-electric or electro-magnetic 

 machine. Electric attraction. 



Electro-magnet. 



Magnetic Energy, Heat . • \ b. 

 (Heat generated on demag- 

 netizing a magnet ) ^ c - 



t Armature attracted by a permanent 

 ( magnet 



(Induced current on demagnetizing 

 a magnet. 



Gravitation Energy, Ileat . 

 (Heat generated by a fall- 

 ing body.) 



Electrical 

 Gravitation 



. Mechanical Energy. Velocity imparted to a falling body. 

 Electrical ' ' 

 Magnetic " 



2. Results cf Best Determinations. 



On the basis of this table of methods I have arranged the following 

 table, showing the principal results so far obtained. 



In giving the indirect results, many persons have only measured 

 one of the transformations required ; and as it would lengthen out the 



