1847.1 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



223 



. I was also led, from these results, to inffr tli;it induced currents 

 must traverse the line of ii r^iilroad, and this I found to be the case. 

 .Sparks we seen at the breaks in the coiviiiuity of the rail, with every 

 flash of a distant thunder-cloud. 



Similar efTects, but in a greater degree, must be produced on the 

 wire of the telegraph by every discharge in the heavens; and the 

 pliffinonirna whicli 1 witnessed on the 19th of June in the telegraph 

 office in Philadelphia wire, I am sure, of this kind. In the midst of 

 the hurry of the transmission of the congressional intelligence from 

 Washington to Philadelphia, and thence to New York the apparatus 

 began to wurk irregularly. The operator at each end of the line an- 

 nounced at ihe same time a storm at Washington, and another at 

 Jersey Cily. The portion of the circuit of the telegraph which en- 

 tered llie building, and was connected with one pole of the galvanic 

 battery, happened lo pass within the distance of less than an inch of 

 the wire which served to form the connexionof the other pole with Ihe 

 earth. Across this space, at an interval of every few ujinuies, a series 

 of sparks in rapid succession, was observed to pass; and when one of 

 the storms arrived so near Phil.idelphia that the lightning could be 

 seen, eacii series of sparks was found to be simullaneous with a flash 

 in the heavens. Now we cannot suppose for a moment that the wire 

 was actually struck at the time each flash took place; and indeed it 

 was observed lliat the sparks were produced when the cloud and flash 

 were at the distance of several miles to the east of the line of the 

 wire. The inevitable cone'usion is, that all the exhibition of electri- 

 cal phEEuomena witnessed during the afternoon was purely the etiect 

 of induction, or the mere disluibance of the natural electricity of the 

 wire at a distance, without any transfer of the fluid from the cloud to 

 the apparatus. 



The discharge between the two portions of the wire continued for 

 more than an hour, when the efl'ecl became so powerful, that the super- 

 intendent, alarmed for the safety of the building, connected the long 

 wire with the city gas-pipes, and thus transinitted the current silently 

 to the ground. I was surprised at the quantity and intensity of the 

 current; it is well known, that to affect a cominou galvanometer with 

 ordinary electricity, requires the discharge of a large battery; but 

 such was the c|uantily of the induced current exhibited on this occa- 

 sion, that the needle of an ordinary vtrtical galvanometer, with a 

 short wire, and apparently of little sensibility, was moved several de- 

 grees. 



The pungency of the spark was also, as might have been expected, 

 very great. When a small break was made in the circuit, and the 

 parts joined by the fore-finger and thumb, the discharge transndtted 

 through the hand affected the whole arm up to the shoulder. I was 

 informed by the superintendent, that on another occasion a spark 

 passed over the surface of the spool of wire, surrounding the legs of 

 the horse-shoe magnet at right angles to the spires; and such was its 

 intensity and quantity, that ^dl the wires across which it passed were 

 melted at points in the same straight line as if they had been cut in 

 two by a sharp knife. 



The effects of the povi'erful discharges from the clouds may be 

 prevented in a great degree, by erecting at intervals along the line, 

 and aside of the supporting poles, a metallic wire, connected with the 

 earth at the lower end, and terminating above at the distance of about 

 half an inch irom the wire of the telegraph. By this arrangement 

 the insulation of the conductor will not be interfered with, while the 

 greater portion of the charge will be drawn oflT. I think the precau- 

 tion of great importance at places where the line crosses a river, and 

 is supported on high poles; also in the vicinity of the office of the 

 telegraph, wiiere a discharge, falling on the wire near the station, 

 might send a current into the house of sufiicient quantity to produce 

 serious accidents. The fate of Professor Kichman, of St. Peters- 

 burgh, should be recollected, who was killed by a flash from a small 

 wire, which entered his house from an elevated pole while he was 

 experimenting on atmospheric electricity. 



The dapger, however, which has be in apprehended from the elec- 

 tricity leaving the wire and discharging itself into a person on the 

 road, is, I think, very small; electricity of sullicient intensity lo strike 

 a person at the distance of eight or ten feet from the wire, would, in 

 preference, be conducled down the nearest pole. It will, however, in 

 all cases be most prudent to keep at a proper distance from the wire 

 during the existence of a thunder-storm in Ihe neighbourhood. 



It may be mentioned as an interesting fact, derived from two inde- 

 pendent sources of iufurinaliun, that large numbers of small birds 

 liave been seen suspended by the claws from the wire of the tele- 

 graph. They had in all probability been instantaneously killed, either 

 by a direct discharge, or an induced current from a distant cloud, 

 while they were resting on the wire. 



Though accidents to the operators, from the direct dischage, may be 

 prevented by the method before mentioned, yet the effect on the ma- 



chine cannot be entirely obviiited; the residual current which escapes 

 the discharge along the perpendicular wires, must neutralise for a 

 monieni the current of the battery, and produce irregularity of action 

 in the apparatus. 



The direct discharge from the cloud on the wire is, comparatively, 

 not a frequent occurrence, while Ihe dynamic inductive influence must 

 be a source of constant disturbance "during Ihe season of thunder- 

 storms ; and no oilier method presents itself lo my mind at this time 

 for obviating Ihe effect, but I hut of increasing the 'size of llie batlery, 

 and diminishing Ihe sensibility of the magnet, so that at least Ihe 

 smaller induced currents may not be felt by Ihe machine. It inurt be 

 recollected that the inductive influence lakes place at a distanc- 

 through all bodies, conductors and non-conductois,; and hence no 

 coating that be put upon the wire will prevent the formation of in- 

 duced currents. 



I think it not impiobable, since the earth has been made to act the 

 part of the return conductor, that some means will bi' discovered for 

 insulating the single wire beneath the surface of the earth ; the diffi- 

 culty in effecting this is by no means aa great as that of insulating 

 two wires, and preventing the current striking across from one to the 

 other. A wire buried in the earth would be protected in must cases 

 from the effect of a direct discharge; but the inductive influence 

 would still be exerted, though perhaps in a less degree. 



The wires of the telegraph are too small and too few in number to 

 affect, as sjme have supposed, Ihe electrical condition of the atmo- 

 sphere, by equalizing the quantily of the fluid in different places, and 

 thus producing a less changeable state of the weather. The feeble 

 currents of electricity which must be constantly passing along the 

 wires of a long line, may, however, with proper .study, be the means 

 of discovering many interesting facts relative to the electrical stale 

 of the air over different regions. 



REGISTER OF NEW PATENTS. 



WAGON COVERS AND WRAPPERS. 



Henry Hekson, of Hampstead, in the county of Middlesex, gentle- 

 man, for " a nem fabric, suitable for goods' 7erappcrs, wagon-cortrs, and 

 olhtr li ke purpoises ; and certain processes employed in the maniifacturtt 

 of the sa)«6."— Granted November .'>, IS 16 ; Enrolled May 5, 1847. 



This invention relates to the manufacture of two descriptions of 

 fabrics; one suitable for covering wagons, coaches, or other vehicles 

 &c., and the other for covering light goods, which are not gener.dly 

 exposed to the weather, and for similar purposes. The base of the 

 first fabric is hempen thread ; with which is interwoven, when the 

 fabric is being made in the loom, copper wires, or galvanized iron 

 wires covered with thread (but uncovered may be used, if preferred), 

 or thin strips of cane; the object being to produce a fabric which 

 shall not be liable to be rent or lorn. The wires or strips of cane may 

 oe inserted at from one to six inches apart, according to the strength 

 required, and the thickness of the wires or strips; and thev mav form 

 part of either the warp or weft. For ordinary fabrics. No. 28 wire 

 will be found suitable, and inserted at two inches apart. The fabric 

 is immersed in a vat, filled with tanning liquor, of li cwt. of good 

 oak bark to one hundred gallons of liquor; tlie fabric must he so pro- 

 portioned to the quantity of the liquor, that for every yard there shall 

 be about two gallons of tanning liquor, and to remain in the liquor for 

 about fifty hours, ;.nd kept at a temperature of 15U°; it is tlien re- 

 moved from the vat, and hung up to dry. if the fabric be required tu 

 possess the quality of leather in a greater degree than can be given 

 to it by the above process, this may be effected by subsequentiv im- 

 mersing it, for about ten hours, in a weak solution of gelatine or'albu- 

 men, and repeating this operation two or three times, according to the 

 effect desired to be produced. Instead of the above process of tan- 

 ning, the well-known processes of tanning by exhaustion, or by hy- 

 draulic pressure, may be employed. The fabric is now waterproofed, 

 by first saturating it wilii a composition called by the patentee No. 1 

 and, when that has become dry, coating it with another compositioii 

 termed No. 2. The first composition is formed of one gallon of tur- 

 pentine, one ;poniid of tallow, and one pound of bees' was; and the 

 second is composed of two quarts of raw linseed oil, one quart of boiled 

 linseed oil (rendered drying by the addition of litharge;, one quart of 

 Stockholm tar, and twenty ounces of lamp-black or ground cliarcoal. 

 The fabric is placed upon a hollow iron table or cliesi, heated by the 

 admission of steam into it, and the compositions are applied by nieaiis 



