As I quoted back here, Boston selectman Timothy Newell recorded that on 14 July 1775:
Dorrington his son and daughter and the nurse for blowing up flies in the evening, they are charged with giving signals in this way to the army without.Though Newell didn’t record this detail, William Dorrington was the keeper of the smallpox hospital in the west end of town, and therefore answered to the selectmen. Presumably “the nurse” worked at the hospital as well.
The Dorrington party were examined in court on 18 and 19 July and dismissed on the 26th. Fellow prisoner Peter Edes later wrote a list of nasty acts by the prison officials that included: “Also three dollars was demanded of Dorrington, and the provost kept his bed and bedding six days, and then delivered them up.”
A few months back John A. Nagy, an author who’s looking into Revolutionary War espionage, asked me what I thought “blowing up flies” meant. The Dorringtons’ fellow prisoners used that phrase and called the family “the Fly blowers,” so apparently it didn’t strike them as odd or in need of explanation.
I found another use of the phrase in the Annual Register for 1794, which gives a clearer sense of the act:
Brighthelmstone. A dreadful accident happened yesterday at Hove, in consequence of the inadvertency of a boy who was attempting to blow up flies with gunpowder, at a public-house. He had formed a train, for this purpose, across the side of the room, at the end of which stood a closet containing a great quantity of powder. A spark of the former unfortunately got among the latter, and, such were the dreadful consequences of the explosion, that the boy had one of his eyes blown out, and his face most shockingly mangled.So it looks like “blowing up flies” meant exactly what it looks like: using gunpowder to set off small explosions in order to kill flies. A lot of flies, I hope, given the trouble and risk involved. Given that cleansing the smallpox hospital involved “smoking” the rooms and linens, however, perhaps people thought explosions could kill two types of bugs with one blast.
Two soldiers have likewise suffered so much by the same, that their lives are despaired of. There were several more in the apartment, who escaped unhurt. That part of the room, however, where the gunpowder stood, was intirely knocked down by the violence of the shock, and the house considerably damaged.
No doubt the besieged British garrison was on edge and suspicious about explosions in town. And the Dorringtons were “blowing up flies” at night, out on the side of the peninsula closest to the Continental troops in Cambridge. So they might have been lucky to be let out so quickly.