On a Thnfor properly observing Fire-lall Meteors. 131 



and in the Transactions of our own Royal Societj', (or, see Dr. 

 Charles Hutton's Diet. Fire Ball.) will immediately perceive 

 that a very material article is omitted therein ; and, indeed, one 

 of the most essential for obtaining by induction a satisfactory 

 theory of these meteors; which is, at the time of observation to 

 connect therewith — the known local peculiarities of the station 

 or point of view respecting atmospherical pressure, refractions, 

 &."<■. — the thermometric and hygrometric affections, and particu- 

 larly the magnetic and electric indications at the same time. 

 From this combination it may be then possible to form a general 

 deduction upon true geological principles, and obviously result- 

 ing from well-known natural causes. 



I am, sir, yours, &c. 

 Islington, Jan. 7, 1818. H. ClaRKE. 



A Plan for ol'serving the Meteors called Fire-halls. By Nevil 

 Maskelwne, D.D.F.R.S. and Astronomer Royal. 



Five meteors, of the kind which from their appearance are 

 generally called fire-balls, have been seen of late, in the space of 

 a few weeks, viz. on August 18, Sept. 2(J, October 4th, I9th, aad 

 29th, which seems to indicate that they appear more frequently 

 than is commonly imagined. The curious and extraordinary ap- 

 pearances whicii they exhibited, show them to be deserving 

 more attention than lias been hitherto given them. For want of 

 a series of proper observation';, little progress lias been made to- 

 wards accounting for their phcenomena. Tlie greater part of 

 those who have seen them, not being j)reviousIy acquainted with 

 the circumstances they ought to attend to, have made observa- 

 tions too imperfect to answer t'.iat purpose. It is therefore to be 

 wished that all persons who may happen to see a meteor, would 

 attend to the following particulars, and set down their remarks 

 ae soon as they can after thev see it, while the impression made 

 by the meteor is full and fresh in their nieinory, before it is vi- 

 'iated by their own after-thouehts, or the accounts received from 

 iithcr observers. Such after-tlioughts may be of great use : but 

 iljeir own genuine original observations are cliieilv to be wished 

 tor by any one wiio is to calculate the tract of the meteor. 



Tlie particulars to be attended to are these : — 



1st. The precise tintc of its ajjpearance. 



2d. Its apparent altitudes and bearings at its first appearance, 

 r.t its greatest elevation, at its bursting, and at its disappearance, 



3d. Its figure, and the diameter of the body when at the 

 greatest apparent altitude, compared with that of the sun or 

 rnoon at the same altitude ; the brightness and colours of its 

 light, and the degree of Illumination which it gave; and to make 



1 2 a sketch 



