302 . Analyses of Books. [AprRit, 
Dr. Maskelyne’s formula for determining the height of moun- 
tains by the barometer is as follows : 
1. Take the difference of the tabular logarithms of the observed, 
barometrical heights at the two stations, considering the first 
four figures (exclusive of the index) as whole numbers. 
2. Observe the difference of Fahrenheit’s thermometer at the 
two stations ; multiply this difference by 0°454, and add or sub- 
tract this product, according as the thermometer was highest at 
the HERE or low station, which will give an approximate height. 
3. Take the mean between the two altitudes of the thermo- 
meter, and find the difference between this mean and 32°. 
Multiply the approximate height by this diderence, and the 
product by the decimal fraction 0:00244, This last correction 
being added to, or subtracted from the approximate height, 
according as the mean. of the two altitudes of falrenheit’s ther- 
mometer was greater or less than 32°, will give the true height 
of the upper station in English fathoms. 
Dr. Hutton’s rules are as follows: 
1. Let the heights of the barometer at the top and bottom of 
any elevation be observed as near the same time as may be, as. 
also the temperatures of the attached thermometers, and the 
temperature of the air in the shade at both stations, by. means of 
detached thermometers. 
2. Reduce these altitudes of the barometer to the same tem- 
perature by augmenting the height of the mercury m the colder. 
temperature, or diminishing that in the warmer by its y— part 
for every degree of difference between the two. 
3. Take the difference of the common logarithms of the two 
heights of the barometer (so corrected), considering the first 
four figures as whole numbers, which will give an approximate 
height. 
4. Take the mean of the two detached thermometers: and for 
every degree which this differs from 31°, take ‘so many times the 
<i; part of the approximate height; and add them, if the mean 
temperature be above 31°; but subtract them if it be below 31°, 
and the sum or difference will be the true altitude in fathoms. 
These formulas have been somewhat modified, and, perhaps, 
improved by subsequent philosophers. But the improvements 
would not remove the striking anomalies observable in the 
preceding table from Mr. Greatorex’s: observations. 
VIL. On the different Methods of constructing a Catalogue of 
the fixed Stars.. By J. Pond, Esq. F.R.S. Astronomer Royal.— 
This paper contains a set of judicious observations highly worthy 
of the attention of astronomers. But as it would be in vain to 
expect that a subject of such a nature would be interesting to 
readers in general, we shall not attempt an abstract of it. We 
learn a curious fact from this paper, which redounds highly to 
the credit of the instruments at the Greenwich Observatory and 
of the Astronomers Royal. The late Dr. Maskelyne had con- 
