220 



BULLETIN OP THE BUREAU OP PISHERIES. 



variable in these lakes, and to it are due most of the striking differences in the work 

 required to warm the deeper strata. In the 30 to 40 m. stratum of Canandaigua Lake, 

 for instance, it required about 70 g. cm. to put 1,230 cal. into place. In the corre- 

 sponding stratum of Cayuga Lake it required 93 g. cm. to place 1,400 cal. The 

 difference in calories is about 14 per cent, in work over 30 per cent. This is mainly 

 due to the difference in loss of density. At 6.1°, the temperature of Canandaigua Lake, 

 this is 35 points,' and at 6.4°, the temperature of Cayuga Lake, it is 46 points, or over 

 30 per cent greater. 



Table 4 shows that a great amount of work is necessary to produce by mixture 

 the high temperature of the upper strata; it shows also that an almost incredibly small 

 amount of work is needed to carry considerable heat to great depths if only it involves 

 but little rise of temperature. Note, for example, Seneca Lake, where 42 cal./cm.^ 

 of surface are transported to a mean depth of 55 m. for an expenditture of about i g. cm. 

 On the other hand, in the corresponding stratum of Canandaigua Lake, each gram 

 centimeter of work transports only about 18 cal. The difference is due to the much 

 greater rise of temperature in the smaller lake — reaching 5.2° instead of 4.5° in Seneca 

 Lake. 



Table 5. — Detail for Seneca Lake op the Facts op Distribution op Mean Summer Heat Income. 



{NOTS. — T.=temperature in degrees centigrade; i-D=loss of density due to warming; RTXZ=factor, reduced thickness 

 multiplied by depth. Direct=work done in behalf of stratum in question; Dist.=work done in stratum in question; Cal.= 

 calories of summer heat income in stratum. All expressed in imits per square centimeter of lake surface. See fig. 3. p. 

 229; also Birge, 1916, p. 349i 355-1 



Depth in meters. 



T. 



i-D. 



RTXZ. 



Direct work. 



G. cm. G. cm, 



Dist. work, 



G. cm. 



Cal. 



Depth 



in 

 meters. 



CaL 



o-i 



1-2 



2-3 



3-4 



4-5 



5-6 



6-7 



7-8 



8-9 



9-10 



lo-ii 



11-12 



12-13 



13-14 



14-15 



15-16 



Z&-17 



17-18 



18-19 



19-20 



20-25 



25-30 



30-40 



40-50 



So-60 



60-70 



70-80 



Below 80 . 



Total, 



20.4 

 20. 2 



20. 2 

 20. I 



20. O 



20. O 

 19.9 



19-8 

 19, 7 

 19.7 

 19.6 

 19-5 

 19-3 

 18.8 

 18.6 

 17-4 

 i6, o 

 14-8 

 13-6 

 12. o 

 10. 6 

 8.0 

 6-3 

 5-4 

 4-6 

 4-5 

 4-3 



o. 001853 

 iSis 

 181S 

 1790 

 1770 

 1770 

 1749 

 1729 

 1708 

 1708 

 1688 

 1668 

 1628 

 1519 

 1491 

 1269 

 1030 

 0844 

 0674 

 0475 

 0328 

 0124 

 0042 

 0016 

 0003 

 0002 



49-5 

 147 

 240 

 333 

 423 

 512 

 592 

 67s 

 748 

 827 

 914 

 989 

 1,076 

 1. 147 



Ij232 

 1,304 

 1,370 



1. 453 



1,517 



1,580 



9,050 



10, 735 



26, 040 



31,130 



35,120 



38,005 



45,280 



9.2 



26.8 

 43-7 

 59-6 

 74-9 

 90. 6 

 103.6 

 117. 8 

 127.9 

 141-4 

 154-5 

 165.2 

 176- o 

 176. o 

 183.3 

 165.7 

 141- 1 

 123-4 

 102. 4 

 74-6 



581-3 



8SS-0 



607- 2 



296-8 



132- 7 



109- 2 



49-8 



10- 5 



7-6 



4-5 



284-6 

 266.5 

 248.8 

 231-5 

 213.6 

 197-0 

 180-8 

 164-9 

 149-6 

 134.6 

 119- 8 

 105. 2 

 90-9 

 76-5 

 65-6 

 53-0 

 43-3 

 35-6 

 29-3 

 24- 6 



826.9 



185-8 



80.8 



35-7 



29- 5 



9-1 



2.9 



1-3 



•4 



1,624 



1, 588 



i>555 



Ii530 



1,504 



1,488 



1.447 



1,422 



1,382 



1,366 



1,357 



1.333 



1,316 



1,258 



1,241 



1,126 



996 



896 



787 



648 



2,653 



1,560 



1,714 



969 



485 



263 



165 



347 



2,868-8 



2,874-4 



34. 020 



2, 874- 4 



2, 589- 8 



3, 323- 3 



2,074- 5 



1, 843- o 



1,629.4 



1.432-4 



1,251-6 



1, 0S6. 7 



937-1 



802-5 



682-7 



577-5 



486-6 



410- 1 



345-5 



292-5 



249-2 



213.6 



184-3 



159-7 



78-9 



43-2 



13-7 



4. 6 



1-7 



•4 



34, 020 

 32,396 

 30,808 

 29, 253 

 27, 723 

 26, 219 

 24. 731 

 23,284 

 21,862 

 20,480 

 19, 114 

 17.757 

 16, 434 

 15. 108 

 13,850 

 X2,6»9 

 11.483 

 10,487 

 9.591 

 8,804 

 8,156 

 5,503 

 3,943 

 3,229 

 1,260 

 775 

 512 

 347 



' By a "point" is meant a decrease in density of one part per million. The density of water at 6.1 as compared with that 

 at 4.0° is 0.999965. Thelossindensityis. therefore, 0.000035 and this represents the loss in weight of the lighter surface water at 

 6.1°, and, therefore, is one factor in determining the work to be done in pushing it down into deeper and cooler strata. For con- 

 venience in computation this factor is taken as a positive quantity and a whole number is stated as 35 points. (See Birge zgi6 

 P-391.) . • • 



