20. In operating upon large subjects, entire animals, &c., the constant pressure required by the piston of the syringe grows wearisome, besides occupying both hands, which is sometimes inconvenient when working without assistance. To obviate this, another way of driving the syringe was published in the “Micrographic Dictionary” which I will quote here:--“We have therefore contrived a very simple piece of apparatus, which any one can prepare for himself, and which effects the object by mechanical means. It consists of a rectangular piece of board, two feet long and ten inches wide, to one end of which is fastened an inclined piece of wood (equal in width to the long board, and one foot high). The inclined portion is pierced with three holes, one above the other, into either of which the syringe may be placed--the uppermost being used for the larger, the lowermost for the smaller syringe; and these holes are of such size as freely to admit the syringe covered with flannel, but not to allow the rings to pass through them. The lower part of the syringe is supported upon a semiannular piece of wood, fastened to the upper end of an upright rod, which slides in a hollow cylinder fixed at its base to a small rectangular piece of wood; and by means of a horizontal wooden screw, the rod may be made to support the syringe at any height required. The handle of the syringe is let into a groove in a stout wooden rod connected by means of two catgut strings with a smaller rod, to the middle of which is fastened a string playing over a pulley, and at the end of which is a hook for supporting weights, the catgut strings passing through a longitudinal slit in the inclined piece of wood.” When in use the syringe is filled with injecting fluid, and passed through one of the three holes which is most suitable. The object being placed so that the pipe and syringe can be best joined, the rod and strings are set in order, and a weight placed on the hook. The stopcock must then be opened gradually, when the operator will be able to judge whether the weight is a proper one or not: if the piston is driven with any speed, there is danger of injuring the subject, and less weight may be used; if, however, the piston does not move, more must be added.