The Chambers Rod and the Phoenix Mill Fire

The Chambers Rod and the Phoenix Mill Fire.

BY W. H. PRATT.

The Phoenix Mill, corner of Western Avenue and Front Street, was destroyed by fire at the time of a violent thunder-storm on the night of Sunday, the 26th; and as it was provided with the Chambers Lightning Rod, it became a matter of especial interest to learn whether it was destroyed by lightning. If so, it would be the first instance of the kind, so far as we had ever learned.

Some time since I went to investigate the matter and learned from Mr. Pahl, one of the proprietors, that he had supervision of the premises at the time; and that the mill had been stopped for several weeks, for the purpose of making some additions and alterations, of which work he also had charge. He informed me that the rod had not been changed nor interfered with in any way, bat remained just as it was left by the parties who furnished and placed it there.

It ran around the edge of the rectangular roof, enclosing an area of about fifty by thirty feet, and was about eighty feet from the ground, and high above all surrounding buildings.

The mill had been cleaned out so that there was certainly no considerable accumulation of dust in any part, and they were always especially careful that no grease should be dropped or accumulate anywhere, so that the idea of spontaneous combustion could not be entertained for a moment. Occurring as it did, in the midst of the storm of wind, lightning and heavy thunder, it was very natural to conclude that it was probably struck by lightning; but I wished to find direct evidence, one way or the other, if possible.

Examination of the premises could afford no clue, as the whole concern, lightning-rod and all, was engulfed in the fiery furnace very soon after the tire broke out.

Mr. Pahl told me that the watchman at Schricker & Mueller's sawmill close by, had seen the lightning strike the mill. I went and questioned the watchman, who seemed a very intelligent man, and he informed me that he was standing near the office door — he showed me the spot — in full view of the whole upper part of the flour mill at a distance from it of about 250 feet, with his face in that direction, and watching the play of the lightning in the heavens, when he saw a vivid flash across the sky before him, directly to the top of that building; and instantly, scarcely, if at all, separable from it in time came the thunder crash. He was, of course, fully aware that the mill had been "struck." Almost immediately there poured forth from it a volume of smoke and then of flame, so that it seemed, as he expressed it, as if "it must have made a big hole" in the roof or walls.

We must probably he forced to the conclusion that the Chambers rod is, like all lightning rods, not infallible; and the rod on the Phoenix Mills must be placed in the category of failures. All experience seems to show that no lightning rod affords complete security against violent lightning discharges. Their chief usefulness, probably, is as equalizers, tending to the restoration of equilibrium of disturbed electrical conditions, and thus to prevent, modify or weaken the disruptive discharges. In this view there seems to be no good reason for assuming that the Chambers rod is useless. How many lightning discharges have been prevented by lightning rods, or to what extent they have been weakened, can of course, in the nature of the case, never be known.

It may be assumed that, to be at all efficacious even in this way, the rod must have a good ground connection, but this, as I believe, is not proven, and some experiments apparently point directly to the opposite conclusion.

We very well know that every sharp point or edge of a conductor or a body in the condition of electrical tension, affords an opportunity for the escape of that tension, just as surely as that a hole in a hose filled with water at a high pressure allows a portion to escape, and thus diminishes the pressure.

From all experiments and investigations, as well as from theoretical considerations, it appears that the best security possible would be afforded to buildings by having extensive metallic surfaces, with many sharp edges, points and corners, — the larger the surface, and the more points and rough edges the better — whether connected with the earth by conductors or not; and this latter condition may be a matter of minor importance.

There seems to me to be no reason to fear that the rod increases the danger of injury by lightning under any circumstances. If it has any effect it must be to diminish the danger in a greater or less degree. Otherwise we must also condemn all metallic railing and ornaments which are so common on the tops of buildings.