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since I feel it to be presumptuous in me to offer aught to the scientific 

 world intended to compete with the productions of so learned a physi- 

 cist and physiologist as Yolkman. My duty, however, prompts me not 

 to yield to such feelings ; and so, with a firm conviction of its worth, I 

 proceed to the description of my Ha3modromometer . In my description 

 I beg to refer to the diagrams, such as they are, which I have drawn, 

 in order to render the details more intelligible. 



The complete instrument, as seen in the drawing (Fig. 1), consists 

 of the copper support, to which is attached, by means of the fasteners 



Fig. 1. 



(a, a, a), the glass index tube, furnished with its arrangements of 

 stop-cock (h), and piston (c). The free extremities of the glass tube 

 extend slightly beyond the support, so as to be more readily connected 

 with the cut ends of the artery. Near the centre of the support is a 

 chronometer, the hand of which describes the circle in one minute. At 

 one side of the support are represented the heaters (e), which are sent 

 home into their respective cavities. 



The shape and construction of the support will be readily seen on 

 glancing at the diagram. It is made of copper, which is a very good 

 conductor of heat. At its side are the openings of the two cavities, which 

 extend longitudinally along it for about three-fourths of its length ; 

 into these cavities run the iron heaters, furnished with handles of porce- 

 lain, so as not to burn the hands of the operator when they are to be 

 removed from the fire. The heaters are kept in their position in the 

 support by means of a long iron pin, which runs through a hole in the 

 support and heaters, as seen in the drawing (/). 



_ The index tube will be seen to have a peculiar form ; and, simple as 

 this form looks, it has cost me much thought and consideration to de- 

 termine on it as being that which would be least likely to prove detri- 

 mental to the flow of fluid in it. 



This tube will be observed to have no sudden angles in its course. 

 The fluid on entering into it is not met by an opposing wall, as in Yolk- 



