. 
REGNAULT’S HYGROMETRICAL RESEARCHES. 655 
of humidity, and to compare them with those which have been 
obtained by direct weighing. 
To judge more easily of the course of the experiments I have 
adopted the formula 
07429 (¢ — 7’) 
tes SL 
as 610 — ?' vhs 
The values P, of the fraction of saturation inscribed in the 
table have been calculated with the value of # found by means 
of this formula. 
TaBLeE I.—Evxperiments on the Psychrometer made in the large 
quadrangle of the Collége de France. 
hes elie" Weight Degrees of saturation. 
co ag Moist thermometers. 5 a ie Kinde. ||Calculated: 
x 
& t. tv, ho. D. 4. Fe 
Series l. 
° ° ° ° mm grm. 
12-12 7:07 7:10 5°04 764°38 | 0-270 0:396 0:424 
12°54 761 763 4:92 764:35 | 0°3035 | 0:466 0-474 
14:07 7:56 7:60 6:49 764-43 | 0-2595 0°362 0°356 
15-24 9-52 9°53 5°72 762°42 | 0°324 0-420 0:417 
16-68 10-06 10:06 6°62 760:42 | 0319 0:377 0-396 
17°88 8°27 8-30 9°60 75489 | 01755 | 0-193 0:197 
13°18 8:87 8:97 4:26 756'43 | 0°340 0506 0-551 
18-08 11-66 11-68 6-41 754-72 | 0:399 0438 0-438 
18-47 10-60 10°63 7°83 75436 | 03245 | 0-344 0:337 
18-06 | ...... 12°51 5°55 75110 | 0:436 0-496 0°507 
13:12 9:39 9°46 3°69 749°38 | 0°398 0597 0-609 
9-39 5°62 5-68 3:74 737-09 | 0:287 0°545 0554 
7:16 5-29 5-31 1:86 748-71 | 0:332 0-731 0-750 
Serres I].—Small Psychrometer. 
17-90 IGS) i Piwnsts 6-11 752°61 | 0-392 0°439 0°463 
17-70 LDS one pale 5:99 752-50 | 0°405 0-454 0-466 
14°51 11:06 | ...... 3°45 755°57 | 0:455 0°628 0-646 
16°58 12°24 areahld 4:34 75510 | 0:466 0563 0°589 
16°33 date | scesne 3°99 754:70 | 0°485 0594 0°617 
16-05 E2SAR IE Secces 32] 754-65 | 0543 0°677 0:685 
The fractions of saturation, calculated by means of the for- 
mula, agree here in a very satisfactory manner with those which 
are found by direct weighings. But the agreement was much 
less perfect in the lower temperatures and in a very humid air, 
as may be judged by the following Table, which contains expe- 
riments made under circumstances quite similar in December 
1842. The psychrometer employed in these last experiments 
