35(5 



Lightning Rods. 



Vol. IX. 



along a rod, however closely it may be in- 

 vested by glass, resin, wax, sulphur, or other 

 nonconducting substance, we need not fear 

 any material diminution of its conducting 

 power from either rust or paint. 



Experiments seem to show, that copper is 

 a better conductor of the electric fluid than 

 iron, and is therefore preferred for conduct- 

 ors, but the high price of that metal is a 

 valid objection to its general employment, 

 so long as a cheaper material is found fully 

 tQ answer the purpose. 



In view, therefore, of all that appears to 

 have been ascertained in relation to this 

 subject, I would recommend common jive- 

 eighths or three-fourths round iron, without 

 paint or any other extraneous covering, as 

 being entirely sufficient for the purpose — 

 and believe that it never has failed to afford 

 the desired protection, when the other condi- 

 tions necessary to a perfect conductor have 

 been attended to. 



Where it can be conveniently done the 

 bars should all be welded into one ; but as 

 this can seldom happen in long rods, great 

 attention should be given to make neat 

 joints. The top of the lower bar should be 

 drawn into a conical point three inches long 

 or more, and a corresponding socket formed 

 on the lower end of the upper bar to sit 

 close upon it. When the joint is accurately 

 made in this manner, the fluid can readily 

 pass from one bar to the other — water can- 

 not enter the joint, and where the attach- 

 ments of the rod are properly made, so as to 

 allow it to slide in the fastenings, the weight 

 of the upper portion will keep the surfaces 

 in complete contact. 



2. The foot of the rod. — As the rod is 

 more exposed to corrosion from moisture 

 near to and beneath the surface of the earth, 

 it is proper to make the lower part of larger 

 iron. It should be so bent at the surface as 

 to pass off from the foundation of the build- 

 ing at an angle of about 45 degrees. And 

 it is a good precaution to place a few pieces 

 of old stove or plough castings, or other old 

 iron in contact with the bottom of the rod, 

 and then partially to fill the hole with char 

 coal or blacksmith's cinders. These sub 

 stances being more retentive of moisture, 

 and better conductors of electricity than 

 mere earth, especially when diy, will form 

 a more perfect connexion between the rod 

 and the ground. But whatever precautions 

 of this sort may be adopted, it is always ab 

 solutely essential to the successful operation 

 of the rod, that its foot shall communicate 

 with moist earth. Unless it penetrates deep 

 enough to do this, it will afford only a pre- 

 carious protection. And it is necessary that 

 it should do this in all situations and seasons 



however dry, for it is in these that the great- 

 est danger is incurred. From six to ten feet 

 may be a sufficient depth in ordinary situa- 

 tions, but in very dry banks where barns are 

 frequently located, this depth will be insuffi- 

 cient. In all such cases I would advise the 

 rod — or a branch communicating with it — 

 to be carried into a well or spring of water, 

 wherever it can be done. I do not hesitate 

 to affirm, that a very large proportion of the 

 accidents which have occurred where con- 

 ductors were in use, have been occasioned 

 by a defective communication between the 

 rod and the earth. Owing to this defect, the 

 rod is often placed in the same condition as 

 the wire e, fig. 8, Prop. 25. It cannot dis- 

 charge the electricity from the cloud — an 

 explosion takes place to the point as the 

 nearest object, and then passing down the 

 rod its progress is arrested at the foot, by 

 the want of a better communication with 

 the earth, and it is forced to pass by a lateral 

 explosion to the nearest and best conducting 

 part of the building. This is a very frequent 

 occurrence, and is fully explained by the 

 beautiful experiment just referred to. While 

 such accidents ought to teach us the neces- 

 sity of due attention to every particular in 

 ithe construction of conductors, they should 

 also inspire us with full confidence in their 

 I efficacy when properly constructed. I would 

 {refer the reader to the Farmers' Cabinet, vol. 

 5, p. 199, for some appropo remarks upon the 

 subject by Observer. 



3. Support and attachments of the rod. — 

 It is usual to attach conductors to the end of 

 the buildings by means of iron eyes or blocks 

 of wood with bottle necks, or pieces of horn 

 inserted in them. The attachments are of 

 little consequence so long as the rod per- 

 forms its legitimate duty of silently dis- 

 charging the electricity; but they maybe- 

 come of much greater importance, if from 

 any cause an explosion should take place. 

 In case of a stroke, the attachments ought 

 to be of a nonconducting material, so as to 

 prevent the fluid from passing into the build- 

 ing. A greater degree of security may how- 

 ever be obtained by attaching the conductor 

 to a pole instead of the building, and sup- 

 porting it with stays from the barn. It may 

 be remarked in this connexion, that in many 

 situations the back of the barn at one side of 

 the door affords more moisture and a more 

 eligible site for the rod. 



Franklin. 



Sixth month 1st, 1845. 



Roses that bloom the whole season may 

 be propagated by budding, grafting or layer- 

 ing — the latter is preferable, and makes very j 

 permanent plants. 



