100 Foreign and Miscellaneous Intelligence. 



Lbs. 



The first result is from the mean force of each horse in six 



teams of two horses each team, upon light sandy soil . =156 

 The second result is from seven teams of two horses each 



team, upon loamy ground, near Great Berkhampstead . rr 154 

 The third result is from six teams of four horses each team, 



with old Hertfordshire ploughs = 1 27 



The fourth result is from seven teams of four horses each team, 



upon strong stony land (improved ploughs) = 167 



The fifth result is from seven teams of four horses each team, 



upon strong stony land (old Hertfordshire ploughs) . . = 193 

 The sixth result is from seven teams of two horses each team, 



upon light loam = 177 



The seventh result is from five teams of two horses each, upon 



light sandy land = 170 



The eighth result is from seven teams of two horses each team, 



upon sandy land = 160 



" The mean force exerted by each horse from fifty-two teams, or 

 one hundred and forty-four horses, = 163 pounds each horse; and 

 although the speed was not particularly entered, it could not be less 

 than at the rate of two miles and a half per hour. 



" As these experiments were fairly made, and by horses of the 

 common breed used by farmers, and upon ploughs from various 

 counties, these numbers may be considered as a pretty accurate 

 measure of the force actually exerted by horses at plough, and which 

 they are able to do without injury for many weeks ; but it should 

 be remembered that if these horses had been put out of their usual 

 walking pace, the result would have been very different. The mean 

 power of the draught-horse, deduced from the above-mentioned ex- 

 periments, exceeds the calculated power from the highest formula 

 of Mr. Leslie;" which is as follows: (15 v)* =: pounds avoir- 

 dupois for the power of traction of a strong horse, and (12 v) 2 

 = pounds traction of the ordinary horse, v velocity in miles per 

 hour*. 



4. ON THE CHANGE OF VOLUME OCCURRING WHEN BODIES 

 COMBINE TOGETHER. 



An experimental examination of the change of density induced by 

 combination has been undertaken by M. P. Boullay, with a view to 

 ascertain whether any general law could be deduced by which might 

 be obtained an insight into the density of substances generally when 

 in combination. His first care was to obtain the specific gravities 

 of many bodies, simple and compound, to a high degree of accuracy, 

 and in this respect every precaution appears to have been taken. 

 Then comes the point principally under discussion: either the spe- 



* Phil. Mag., N. S., viii. p. 22. 



