Mechanical and General Science. 361 
2. Levels in London above the highest Water-mark. 
eet. inches. 
North-end of Northumberland-street, Strand . 19 74 
North of Wellington-street, Strand . 5 a 1 Shs 6 
North of Essex-street, Strand : ° ZTE 
West of Coventry-street . ‘ : : - 52 0 
South of St. James’s-street . F . . 13. 3 
South of Air-street, Piccadilly . .  . 49:8 
North of St. James’s-street . . .« . 46 7 
West of Gerrard-street . . . e 61 4 
North of Drury-lane~ . : : : Pe NE 
South of Berner’s-street : . . - 74 3 
South of Stratford-place . : : . » 59 A 
North of Regent-street : : = . 76 0 
South of Orchard-street . ‘ ; : - 70 A 
North of Cleveland-street . bp wets : 80 10 
Centre of Regent’s Circus " . ant 77.02 
North of Gloucester-place . 5 ~ mys a ORES 
North-side of Aqueduct crossing Regent’s Canal 102 6 
Opposite south-end of King-street, Great George-st. 5 6 
The whole of Westminster, except the Abbey and part of Horse- 
ferry-road, is below the level of the highest tide. 
N. M. Mag. xii. 206. 
3. On the comparative Advantage of Coke and Wood as Fuel. 
Some trials have been made by M. Debret on the heating power of 
coke and wood, when consumed in stoves, at the Royal Academy 
of Music. Two similar stoves were heated, one by wood and the 
other by coke, and the temperature of the exterior, taken at some 
distance from the fire. The temperature of the flues was at first 
9° c., and the mean temperature, at the end of six hours, was, by 
the wood, 13° c., by the coke, 16° c.; so that the increase by the 
wood was 4°, by the coke 7°. These effects were produced by se- 
venty-three kilogrammes, (103 pounds) of wood, worth three and a 
half francs, and twenty-four kilogrammes, (53 pounds) of coke, 
worth one franc eighty cent. 
During the progress of this experiment another stove had been 
heated for several hours with wood, and the temperature had not 
risen above 13°, ‘The use of coke very quickly raised it to 15° or 
‘16°. Hence it is concluded, and with reason, that coke is. much 
preferable for these purposes to wood; but where thie stove is 
small the mixture of a little wood with the coke is recommended to 
facilitate the combustion. —Bzb. Univ. xxv. 237. 
4. Vicat on burning of Limestone or Chalk.—¥rom some experi- 
ments formerly made by M. Vicat, that philosopher was induced to 
conceive, that probably an imperfect calcination of limestone would 
