VOL. XLVir.] PHILOSOPHICAL TRANSACTIONS. 208 



the canula is much shorter than ordinary. This canula is represented separate 

 in fig. 3 : but there ought to be several, of different lengths for difFei'ent cases. 

 On the upper part of this canula are two circles, each fastened to a different 

 piece. These pieces are exhibited separate in fig. 4, and they are made so as to 

 be screwed on each other. These circles are somewhat concave in their surfaces, 

 which correspond reciprocally ; so that their circumferences touch, while there 

 is a tolerable vacuity towards their centre. By means of this simple mechanism, 

 Mr. le Cat applied the plaster x, with a hole in it, on the lower circle a, whose 

 screw passes into the hole of the plaster : this done, he screws the upper piece 

 B on the lower a, and he squeezes the plaster tight between these 2 circles. 

 The instrument becomes then as in fig. 5 . The plaster, which he had chosen, 

 is that of Andreas a Cruce ; but one may use Burgundy-pitch, or any other 

 powerful emplastic, at pleasure. His plaster was 3 inches broad. To the upper 

 end of the canula he adapted a very exact silver stopple c, fig. 3. The part, 

 where he intended to make the puncture, was shaved, wider than the plaster, 'o 



Thus having prepared every thing, and the canula being armed with its tro- 

 cart, and fortified with the plaster, as it appears fig. 5, h. He performed the punc- 

 ture on Friday the 23d of October 1744, by thrusting in the trocart and canula 

 up to the circles and plaster, which he applied and made to stick in all its parts 

 on the head, by pressing it with his hand and fingers made very warm, and also 

 with hot linen cloths. When the plaster was thoroughly well fastened on, he 

 pulled out the trocart, and drew 4 or 5 oz. of serosity, of a brownish white, or 

 the colour of pale white wine, and somewhat foul; after which he closed the 

 canula with its stopple c. 



By chemical experiments, this liquor was found to be neither acid nor alkaline, 

 being put on the fire, it evaporated quite away, and left at bottom a frothy neu- 

 tro-saline sediment. 



Saturday, Oct. 24, he unstopped the canula, and drew the same quantity of 

 water. The infant was ill on the Sunday; he therefore did not disturb him that 

 day. Monday the 26th he was better. He drew 5 oz. more of water. Tuesday 

 he suffered him to take rest. Every time ttiat he made this evacuation, he bound 

 the head with a strong capeline.* Notwithstanding these precautions, the infant 

 died in the night between Tuesday and Wednesday; and it will presently appear, 

 that this hydrocephalus was of an incurable sort. He opened it, and found the 

 brain applied against the dura mater as usual; but this brain was thin, and as it 

 were spread out; it only formed a kind of thin sack filled with water. He 

 opened, and saw that the disease was nothing more than an excessive dilatation 

 of the two lateral ventricles, by the waters collected there. The glandula pinealjs 



* A bandage peculiar to the head. — Orig. , 



