3. A CONVENIENT INJECTING APPARATUS. 
By W. G. Tight. 
(I’resented 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 place, but when 
an experiment is to be performed in which it is necessary to know 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, but they are generally expensive 
and hard to obtain. 
The mercury column has been utilized in various ways, but the 
volume required 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 also good in its way and easily 
arranged and inexpensive, but no means is provided to regulate the 
pressure and as the bucket becomes empty the pressure gradually falls. 
In the instrument about to be described the following benefits are 
to be derived : Tiie expense is within a few dollars at the greatest ; the 
pressure can be accurately regulated from zero to four pounds (or more, 
if a higher standard is used); the pressure is constant as long as there 
is any liquid in the upper flask ; the pressure can be easily increased as 
injection advances; and requires no attention after it is once started, 
so that a dififlcult injection can be conducted by one person, as he can 
devote all his attention to his canuia and the operation. , It may stand 
on its own merits. 
The following is the description of the instrument used in our 
laboratory, a drawing of which is presented, by A of Plate A, Fig. 4. 
The base board is 2x15 feet; the standard 2 in.x2in. 8ft., gradu- 
ated to feet and half feet. Upon the standard is attached a small 
bracket by means of a friction clamp. 
