[3] PROPAGATION OF WHITEFISH AT NORTHVILLE, MICH. 555 
be drawn barely enough water to supply the actual necessities of the 
hatchery. Accordingly a pond 12 feet wide by 100 long was constructed 
on a narrow plateau. situated across the road diagonally from the 
spring pond, and running nearly parallel with the hatchery. The sur- 
face of the plateau is nearly level with the spring pond, and thus the 
requisite fall of water is maintained. <A trunk fitted at its mouth with 
an adjustable gate runs under the road and conveys the water to the 
cooling or ice water pond, as it is called. 
With the limited amount of water used in the hatchery up to the 
present season, and consequently the comparatively small quantity of 
water to be cooled, this pond proved equal to the requirements. The 
first severe weather of November coated it with ice, which soon increased 
to several inches in thickness, and remained until the following March. 
Water which issued from the earth at a temperature of 47° was thus 
reduced to an average temperature of 35°. The good results obtained 
by the use of this cooling pond have been substantially the same each 
succeeding season up to the present, when, as operations were to be con- 
ducted on a much larger scale, and as the Chase jars, requiring a greater 
volume of water than the hatching-boxes, were to be introduced, it was 
thought to be inadequate. Subsequent events verified the prediction, 
and the additional measures adopted in the premises will be alluded to 
again. 
The trout ponds at the station, six in number, and constituted in one 
series, are situated immediately in the rear of the hatchery, and are sup- 
ported by a spring yielding 200 gallons of water per minute, located 
directly beneath the hatching room. They have contained at various 
times since their construction Brook trout (Salmo fontinalis), McCloud 
River trout (Salmo iridea), California salmon (Salmo quinnat?), Lake 
trout (Salmo namaycush), and Grayling (Thymallus tricolor), but at pres- 
ent are occupied exclusively by the first two varieties named, the latter 
being the property of the United States Fish Commission. 
A feature of both the upper and lower springs, and which indicates 
that their origin and conducting strata are far beyond surface influences, 
is their uniformity of flow and temperature; even the “ oldest inhabit- 
ant” failing to remember any perceptible increase or diminution in their 
yield. They are perpetual fountains, inasmuch as they are uninfluenced 
by protracted droughts, while the variance of temperature between the 
extremes of winter cold and summer heat is less than one degree. 
The amount of water furnished by the lower spring, allof which new 
runs through the ponds in use, is abundantly ample to sustain a second 
series, while the waste from the upper spring could be utilized by sup- 
porting a third series of ponds. 
It will be readily perceived, then, that these springs, both as to their 
relative position and fecundity, are peculiarly fitted for trout propaga- 
tion and culture on an extensive scale; but for whitefish work of sufti- 
cient magnitude to demand the use of more than half the product of the 
