374 PHILOSOPHICAL THANSACTIONS. [anNO J773. 



attention with which he entertained and accommodated us on the day of inquiry 

 Signed, H. Cavendish, William Watson, B. Franklin, J. Robertson. 



Mr. Wilsons Dissent from Part of the preceding Report. — I dissent from the report above, in that 

 part only which recommends that each conductor should terminate in a point. My reason for dis- 

 senting is, that such conductors are, in my opinion, less safe than those which are not pointed. 

 Every point, as such, I consider as soliciting the lightning, and thus, not only contributing to the 

 increase of every actual discharge, but also frequently occasioning a discharge where it might not 

 otherwise have happened. If therefore we invite the lightning, while we are ignorant what the 

 quantity or the effects of it may be, we may be promoting the very mischief we mean to prevent. 

 Whereas if, instead of pointed, we make use of blunted conductors, tliose will as effectually answer 

 the purpose of conveying away the lightning safely, without that tendency to increase or invite it. 



My further reasons for disapproving of points, in all cases, where conductors are judged necessary, 

 are contained in a letter addressed to tlie Marquis of Rockingham, and published in the Phil. Trans., 

 vol. 54. There are other reasons also, which I have to offer, for rejecting points on this particular 

 occasion; and which were mentioned at the committee. Those I shall lay before the n. s. at 

 another opportunity, for the benefit of the public. Aug. "21, 1772. 



IX. Observations on Lightning, and the Method of Securing Buildings from its 

 Effects: In a Letter to Sir Charles Frederick, Surveyor-General of the Ordnance, 



I and F. R. S., By Benj. Wilson, F. R. S., &c. Dated Dec. 8, 1772. p. 49. 



;• Sir, — Your station, as Surveyor-General of his Majesty's Ordnance, being 

 such as makes the subject of this paper particularly interesting to you, I presume 

 an apology for this address will be wholly unnecessary. On an application of 

 the Board of Ordnance to the r. s., in July last, a committee was appointed, to 

 consider of the properest method for securing the magazine at Purfleet from 

 mischief by lightning: which committee reported to the council of that learned 

 body, what they thought necessary to be done on that occasion. The council 

 afterwards transmitted to the board a copy of that report, together with another 

 paper written by myself, in consequence thereof. For, during the consideration 

 of that business, some doubts having arisen in my mind, with regard to the 

 propriety of points, which were proposed to terminate the top of each con- 

 ductor; and those doubts being founded on some experiments and observations, 

 I could not consistently subscribe to that report, nor suppress my opinion, on a 

 subject of such importance. 



Whatever may be the sentiments of others respecting those doubts, yet, being 

 the result of my mature consideration, I thought it my duty to propose them to 

 the committee; and further to express my dissent, in writing, to that particular 

 part of their report: giving, at the same time, some of the principal reasons for 

 such dissent; and referring them, for further satisfaction on this subject, to a 

 letter which is already published in the transactions of the r. s. Agreeable 

 to the declaration at the end of the above dissent, I shall now proceed to offer 

 my further reasons for objecting to pointed conductors. 



