I have found the various sorts of blood pressure instruments defective in one essential—all are bulky. Of the two kinds of mercurial and dial gages, the mercurial is esteemed the best. In an effort to devise an instrument which could be carried on the person without exciting curiosity in private practice, the one illustrated resulted.
The mercurial hinge cock for the mercury is from an instrument made by Tagliabue. I claim only reduction in bulk and consequent mechanical arrangements, the whole apparatus weighing about 1 pound.
The photographs are precisely at the identical focus. Therefore the comparative size open and shut is represented in true proportion.
After careful comparison the mercurial column may be regarded as the most certain to give true results because it is fixed at a zero by gravity and not through artificial standards essential in all other devices dominated by springs as dial instruments, that may