5 
The President read a letter addressed to him by the Baron de Bon- 
stettin, containing inquiries respecting ancient pipes discovered in ex- 
cavations in Ireland. 
The following antiquities were presented to the Museum :— 
1. An iron spear-head found in the county of Fermanagh. Pre- 
sented by Miss Richardson. 
2. A small cinerary urn, found near Cabinteely, on the land of the 
donor. It was discovered in the centre of a small chamber filled with 
a mixture of clay and bone-dust, and covered with a large flag, and about 
two feet of earth. Presented by J. H. Jessop, Esq. 
3. A small glass bottle, found in Ardglass, county of Down. Pre- 
sented by Rev. J. H. Todd, D. D., President. 
4, Five modern Indian coins, and a small ingot of silver. Presented 
by William Kennedy, Esq. 
5. Several copies of the new Index to the Ordnance Map of Ire- 
land, on the scale of one inch to the statute mile, showing the state of 
publication on the 30th of November, 1857. Presented by Captain 
Leach. 
MONDAY, JANUARY 11, 1858. 
Houmerrey Liorn, D.D., Vice-President, in the Chair. 
Arexanper T. Braxetry, Esq.; Maurice Henry Collis, M.B.; Howard 
B. Montgomery, M.D.; and J ohn Purser, Jun., Esq.; s were elected 
Members of the Academy. 
The Rev. Dr. Lioyp read a paper— 
ON THE DETERMINATION OF THE INTENSITY OF THE EARTH'S MAGNETIC 
FORCE IN ABSOLUTE MEASURE, BY MEANS OF THE DIP CIRCLE. 
Tue received method of determining the intensity of the earth’s mag- 
netic force is unsuited to the high magnetic latitudes, the error of the 
deduced force, arising from a given error of inclination, becoming very 
considerable when the latter approaches to 90°. To remedy this defect 
the author suggested, some years since,* another process, in which the 
total intensity is found directly by means of the dip circle,—the pro- 
duct of the earth’s magnetic force into the magnetic moment of the 
magnet being determined by the position of equilibrium of the dipping- 
needle, when loaded with a small weight, and the ratio of the same 
quantities being found by removing the needle, and employing it to 
deflect another substituted in its place. Subsequent considerations, how- 
ever, led him to propose that the dip-circle should be employed only 
in the Jatter part of the process, and that the observation should be 
completed by the known method. 
* See ‘ Proceedings,” January 24, 1848. 
kR. I. ACAD. PROC.—VOL. YI. Cc 
