As a result of these experiments, the State railways of Saxony have, in such cases as were practicable, introduced the annular network of copper. There are some manufacturers, too, who seem desirous of adopting this system, although it has hardly emerged from the period of experiment. The pecuniary advantages that will result from an application of it ought, it would seem, to dispel a large proportion of the criticisms directed against the erection of lightning rods, from the standpoint of expense, and contribute to extend an arrangement which may be considered as a very happy one.
If we compare the square plate with the equivalent annular network, constructed as above indicated, and which should possess, according to the author an external diameter of 1.26 m. and of 3.45 m., we find that:
| The square plate, | 1 mm. thick | weighs 8.9 kilos. |
| " | 2 mm. thick | weighs 17.8 kilos. |
| The annular network | weighs 1.64 kilos. | |
The cost of reticulated ribbon per meter amounts to about 4.4 francs, supposing it to be arranged as shown in the cut.
As term of comparison, we may admit that the following forms are nearly the equivalent of a horizontal, unburied plate one meter square.
| Length. | Diameter. | ||
|---|---|---|---|
| Vertical cylinder | buried | 1.40 m. | 0.13 m. |
| " | " | 1.80 m. | 0.06 m. |
| Vertical bar | " | 2.60 m. | 0.013 m. |
| Horizontal bar | " | 5.20 m. | 0.013 m. |
Horizontal flat ring 1.32 m. in external diameter, and 1.08 m. internal.
Horizontal network 1.01 m. square, and having meshes of the same size as those of the reticulated ribbon.
Horizontal reticulated ribbon 3 m. in length and of the structure described.
Horizontal annular ring 1.26 m. in external diameter, 0.94 m. internal.