30 Dr. Mac Culloch on the 
The next authority is decisive, respecting the rocket, and it is 
found in a manuscript quoted by Dutens, from which Roger 
Bacon is supposed to have derived his knowledge of fireworks. 
The author’s name is Marcus Grecus, and, by the title, the work 
appears to be a general essay on military pyrotechny. 
* Incipit liber ignium a Marco Greco perscriptus, cujus virtus 
et efficacia est ad comburendum hostes, tam in mare quam in 
terra.” The directions for making a rocket are as follows : 
‘“‘ Secundus modus, ignis volatilis hoc modo conficilur. R. libras 
duas sulphuris vivi, libras duas carbonis salicis, salis petrosi 
libras sex: quee tria subtilissime tereantur in lapide marmoria ; 
postea pulvis ad libitum in tunica reponatur volatili vel tonitrum 
facientia. Nota, quod tunica ad volandum debet esse gracilis 
et longa, et preedicto pulvere optime calcato repleta : tunica vel 
tonitrum faciens debet esse brevis, grossa, et preedicto pulvere 
semiplena et ab utraque parte filo fortissimo bene ligata. Nota, 
quod in qualibet tunica primum foramen faciendum est, ut tenta 
imposita accendatur; que tenta in extremitatibus fit gracilis, 
in medio vero lata, et preedicto pulvere repleta. Nota, quee ad 
volandum tunica plicaturas ad libitum habere potest, tonitrum 
vero faciens quam plurimas plicaturas. Nota, quod duplex 
poteris facere tonitrum, ac duplex volatile instrumentum, vel 
tunicam subtiliter in tunica includendo.” 
There is here no direction, it is true, for boring a rocket, with- 
out which it cannot fly by its own recoil ; so that it is possible 
this firework may be a kind of squib, intended to be rendered 
“ volatile” by mechanical means, and not by its own unassisted 
energy. It is not unlikely that this is the very fire of Joinville; 
and the distinction into two parts, the ‘ tunica volatilis,” and 
the ‘‘ tonitrum faciens,” confirms the opinion that these ancient 
projectiles combined the nature of a shell and a_ rocket toge- 
ther. 
It is unnecessary to trace this invention furtherdown. Bacon 
is the mere copyist of Marcus Gracus, or more probably the 
recorder of a composition in common use. But the extent of 
his claims, and of the still worse founded ones of Schwartz, may 
be suffered to remain for a future notice on gunpowder. 
