3- A COXVEXIF.M- INJE( -'IINC; A IM'ARATUS. 



Bv W. Cr. Tight 

 (Presented to the Scientific Association, October 5th, 1889 ) 



There is a demand in every biological laboratory for some sort of 

 an injecting apparatus. The syringe is good in its jjlace, but when 

 an exj^eriment is to be performed in which it is necessary to kn )\v the 

 exact amount of pressure, to have the pressure uniform and constant 

 we must look to other means. To be sure, there are instruments con- 

 structed which meet this demand, bur they are generally expensive 

 and hard to obtain. 



Tne mercury column has been utilized in various ways, but the 

 volume recjuired makes tnat also very expensive. 



The bucket of water hung on a hook on the wall, with a tube 

 leading to a pressure bottle below, is al.-o good in its way and easily 

 arranged and inexpensive, but no means is j^rovided to regulate the 

 pressure and as the bucket becomes empty the pressure gnidially falls. 



In the instrument about to be described the following benefits are 

 to be derived: Tne expense is within a few dollars at the greatest ; the 

 pressure can be accurately regulated from zero to four j)ounds (or more, 

 if a higher standard is used); the pressure is constant as long as there 

 is any lifiuid in the upj^er flask ; the i)ressure can be easily increa.sed as 

 injection advances ; and recjuires no attention after it is once started, 

 so that a difificult injection can be conducted by one person, as he can 

 devote all his attention to his canula and the oi)eration. It nnv^tunl 

 on its own merits. 



The following is the description of the instrument used in our 

 laboratory, a drawing of which is |)resented by .\ of IMate .V, /V- 4- 



The base board is 2x15 feet; the standard 2 in.xjin. Sft., gradu- 

 ated to feet and half feet. U|)an the standard is attached a small 

 bracket by means oi' a friction clamj). 



