324 
Errors in Artiott’s Elements of Physics. 
[Nov. 
74. Describes gravity as a force acting in a line directly to tbe centre of the earth, 
which (setting aside cases of local attr action) can never happen, excepting at the 
equator and poles, owing to the oblate form of the earth. 
84. He describes the swing wheel of a common clock as having 60 teeth, one of 
which escapes the pendulum at each beat ; whereas there are only 30 teeth, one of 
which clears the pendulum at the end of every' 2 heats. 
88. Describes the balance wheel (balance) of a watch as being at each beat, car- 
ried to the extremity of its vibration, by its own momentum, (this would be a perpe- 
tual motion ;) forgetting the use of tire mainspring. 
88. Ascribes the slow going of watches in hot weather, to the dilatation of the 
balance-wheel, [balance,] (which can have no perceptible effect,) instead of the true 
and universally admitted cause, viz. the diminution of rigidity in the balance-spring. 
This is a glaring blunder in a popular treatise on physics. 
104. “ A cannon ball having very great velocity, passes through a ship’s side, 
and leaves but a little mark ; while, one with less speed, splinters and breaks the 
wood to a considerable distance around.” For velocity, read, momentum. A cored 
carronade shot, weighing only 30 or lOlbs. and moving with very great velocity, is 
more destructive than the solid 3hot of the same piece, though weighing 68 or 70 
lbs. and impelled with much less velocity : the latter, pierces a moderate hole ; the 
former, lays two ports into one. A strange mistake for a sailor ! 
104. He countenances the obsolete idea of injury occasioned by tbe “ wind of a 
ball.” 
106. “ On firing a cannon, the gun recoils with as much momentum in it, as the 
ball has.” Read, with many times as much : little of the powder has been ignited 
when the ball quits the muzzle, and the gnn is repelled by the explosive force of 
the remainder acting on the opposite air as a paint efappui, 
121. He states that the Pisan tower was intentionally built with an inclination ; 
contrary to the best authorities. 
191. He states, that the roof of Westminster Hall approaches the limit of possible 
width without support ; although it is not to be compared to the Exercise House at 
Petersburg. 
220. and 346. He advances the novel assertion, that atiniwpAme pressure strength- 
ens the joints of the animal frame : direst them of their tendinous and ligamen- 
tous appurtenances, and the capsular ligament would soon be stretched, and then 
forced in between the bones of the joint, the bones of which would thus be shewn 
to adhere simply by its intervention. 
259. “ The Ganges river 1800 miles from its mouth, is only 800 feet above the 
level of the sea ; to fall which distance, it requires one month.” 
305. He admits without question the old idea, that the vegetable world compen- 
sates for the consumption of oxygen by the animal. 
334. And, throughout the work, he gives the common sucking pump, the name of 
the “ lifting pump,” which is a machine totally different in form and principle. 
354. He speaks of the ocean as being of uniform density, though aware of the 
compressibility of water. 
361, He speaks of the “ boiling” of fish oil and tallow at 600“ : read decom- 
position. 
383. Reasonings on warlike weapons, which wotdd go to prove that mankind 
ought to use only their natural weapons for mutual offence. 
391. “ This process is used for making ice in India, ’’meaning Leslie’s apparatus : 
and P. 393, he docs not remark, when talking of the loss of heat by radiation, that 
this is the process actually used in India. 
393. He calls the hair hygrometer a toy; and Danmell’s, a correct and simple 
instrument; and never mentions the most convenient of all, viz. the moist-bulb 
thermometer- The first has lately been shewn to possess excellencies which were 
overlooked by its inventor ; and the second, though correct, is expensive, fragile, and 
inconvenient for ordinary observation in hot climates. 
395. “ It is tiie rain periodically produced in mountainous regions, which causes 
the extraordinary annual overflowing of many great rivers.” Applicable to the 
Nile only and I'rawadi. 
417. “Tlie reason why the trade winds at their external confines, which are 
about 30° from the sun’s place, appear almost directly east and become more 
nearly north and south as they approach the central line, is * * *”. The reason 
might have been spared, as the fact is the direct contrary of what is here stated, 
for reasons too obvious to be delivered. 
