The function of the rod is twofold, as Franklin well recognized, preventive and preservative. It prevents the stroke, under ordinary conditions, by the action of the points, which send off copious streams of air and dust particles electrified oppositely to that of the cloud. Even at a distance, the dangerous potential of the cloud is reduced by these convection currents and the stroke ordinarily averted. It is clear that ten points are more efficacious than one, and fifty more than five. Hence the number of points which we see distributed over the higher and more conspicuous parts of a building, all of which are carefully connected with the lightning conductor. However well a building may theoretically be protected, conditions will occasionally arise when the rod will inevitably be struck; its preservative function then comes into play, by which it carries the energy of the disruptive discharge safely to earth. The experience of more than a century shows that the lightning-rod affords protection in the great majority of cases; but it would be at least a mild exaggeration to say that it never failed, even when properly constructed. At first, the erection of lightning-rods was opposed in the New World as well as in the Old: some based their opposition to the novelty on religious grounds, saying that, as lightning and thunder are tokens of divine wrath, it would be impious to interfere in any way with their manifestations. This objection was met by saying that for a parity of reason we should avoid protecting ourselves against the inclemencies of the weather. Others opposed the use of the rods on the score that they invited or attracted the flash, which was answered by saying that they attract lightning as much as a rain-pipe attracts a shower, and no more. The death of Professor Richmann, of the University of St. Petersburg, also tended to retard the adoption of the rod for the protection of buildings; but the invalidity of that objection became apparent when the circumstances of the accident became known. Richmann's conductor was like d'Alibard's (1751), an experimental rod, and as such was insulated at the lower end. It was, therefore, not a lightning-rod at all, inasmuch as it was not grounded. On August 6th, 1753, during a violent electric storm, Richmann happened to be close to his exploring rod observing the indications of a roughly-made electrometer, when a sharp thunder-clap was heard, and at the same instant a ball of fire was seen by Richmann's assistant to dart from the apparatus and strike the head of the unfortunate Professor, who fell over on a near-by chest and expired instantly. His assistant was stunned for a while. On regaining consciousness, he ran to the aid of the Professor; but it was too late, the body was lifeless. In recording this tragic event, Priestley, the historian of electricity, says that, "It is not given to every electrician to die in so glorious a manner as the justly envied Richmann."