An introduction to physiology . rn the drum onceround to record the bending under 100 Restore the drum to its former posi-tion, add 100 grams, and make record of theextension at 200 grams. Continue the recordup to 1000 grams. Preserve the curve for ref-erence (page 363). i The scale-pan weighs about 20 grams. THE CHANGE IN FORM 351 The Heavy — It is sometimesnecessary to after-load amuscle lever with weightsfar in excess of those thata light muscle lever willbear without springingand thus altering the ab-scissa. Such heavy loadsare borne by the heavymuscle lever ill
An introduction to physiology . rn the drum onceround to record the bending under 100 Restore the drum to its former posi-tion, add 100 grams, and make record of theextension at 200 grams. Continue the recordup to 1000 grams. Preserve the curve for ref-erence (page 363). i The scale-pan weighs about 20 grams. THE CHANGE IN FORM 351 The Heavy — It is sometimesnecessary to after-load amuscle lever with weightsfar in excess of those thata light muscle lever willbear without springingand thus altering the ab-scissa. Such heavy loadsare borne by the heavymuscle lever illustrated inFig. 60. A tripod of ja-panned malleable iron, 27cm. high and at the base, supportsa femur clamp and a mus-cle lever. The latter isa steel tube 5 cm. long,pierced by a steel axle 9 , revolving betweenheavy brass posts. Thelever weighs about aluminium scale-panweighs about 20 gms. ; itholds one hundred 10-gramweights. The lever may beturned completely over ina backward direction, and. Fig. 60. The heavy musclelever. 1 American Journal of Physiology, 1903, viii, p. xl. 352 THE OUTGO OF ENERGY thus be entirely out of the way. The steel springshown upon the left of Fig. 60 may then be turned tothe right to bring its wire hook into the openingthrough which the scale-pan is reached. The scale-pan may then be attached to this isometric spring andthe spring empirically graduated. When the gradua-tion scale has been written, the milled screw thatholds the isometric spring upon the left-hand post(Fig. 60) may be loosened, the spring turned with thehook up, and the screw made fast again. The lowerend of the muscle may now be attached to thehook upon the spring and an isometric curve written. The screw clamp holding the muscle clamp isinsulated. A binding post upon the muscle clamp,and another binding post upon the right-hand postsupporting the axle of the lever, allow direct stimula-tion of the muscle. This lever serves especially well for the
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