[ x 7 8 1 
berg having obferved, that it broke therein better 
and with a louder Report than in the open Air; 
they both inferred, that neither the impetuous En- 
try of the outward Air, nor that of a Fluid fome- 
what lefs grofs, could be the Caufe of this Shock; 
bccaufe the Receiver of the Air-Pump is void of 
thefe Fluids; and even if a little fhould remain 
therein, it is too much rarefied, and too thin to be 
capable of fuch an Effett. 
Mr. Mariotte , thro' forne Remains of Attach- 
ment to an Opinion, which he had held to rhat 
Time, did net intirely exclude the exterior Air from 
the Caufe of the Phxnomcnon of the Drop ; but 
thought proper to add another to it ; which he 
makes ufe of as a Subftitute in Cafes like thofe of 
the precei. ing Experiment, where the Infufficiency 
of the Air, or of a Fluid nearly fimilar to it, plainly 
appears. 
Mr. Homherg fhews no Indulgence to the exte- 
rior Fluid ; and aferibes the Whole to the new 
Caufe, which is, the Quality of temper’d Glafs, which 
the Drop acquires, like Steel, by being thrown red- 
hot into cold Water. This Tempering, according 
to thefe great Academicians, confers at the fame 
time more Springinefs to the Parts, and lefs Con- 
nection with each other. When a Steel Sword- 
Blade is bent forcibly, it breaks more eafily than one 
of iron; and the Jarring which is occafioncd by its 
Spring, is capable of breaking the other Parts of the 
Biade: And thus we fee, that it generally breaks 
into fevcral Pieces. This Blade is the Image of the 
Lacryma Batavica , or Glafs-Drop. 
This is the Point to which I found Things brought, 
when 1 began to ftudy the Phoenomena of the Gl afs - 
Diop. The 
