Valturio in his _De Re Militari_, 1463, p. 267;[575] but in this case the shell is filled with powder, which in all probability was driven in and compressed as tightly as possible with a mallet and drift.[576] The German writer undoubtedly believed that his shell would burst, for he uses such phrases as “chugel dye da springt” and “zerspringt und zerslecht alls umb.” Neither his shell or Valturio’s would have exploded except under the most exceptional circumstances. The weakness of the shell leads Herr von Romocki to suppose that Valturio’s plate is wrong or grievously exaggerated. I see no grounds for this suspicion: the shell was purposely made weak, so that it might break into two pieces on impact and leave the incendiary charge free to do its work. The missile belonged to the same family as the incendiary projectiles thrown into Roveredo by the Swiss in 1487.[577] There the shell was filled with pitch and rosin: Valturio’s shell was charged with powder, but it was probably compressed tightly into the interior of the shell, and powder, especially serpentine powder, will not explode under such circumstances. When experimenting with gunpowder at New York, Doremus and Budd subjected good modern powder to such hydraulic pressure as to compress it into a solid block without interstices, and on ignition the mass burned quietly away.[578] Valturio’s charge was probably reduced to a state approximating more or less closely to that of the New York powder, and it would have exploded but rarely and occasionally. But the mere fact that the shell was made of bronze is a sufficient proof that it was an incendiary missile. Even had the charge been explosive, a bronze envelope would have been only ripped open by it, not broken into many pieces as iron would have been; a fact which Valturio must have known. Finally, the gunners of the fifteenth century were not in possession of a fuze that would have enabled them to carry on fire with explosive shell. The construction of such a fuze (as will be seen in the section on “Time Fuzes”) was the work of the following century.