384 Lieut. Brown on a Plan for Improving the 



From the result of three different analyses, I was induced 

 to adopt the following numbers as the average : — 



Manganese .... 45*5 

 Arsenic .... 51*8 



Loss and a trace of iron . 27 



100-0 



But this is somewhat an approximation to the numbers of 

 manganese and of arsenic combined atom to atom ; and per- 

 haps the difference depends rather on my unskilfulness than 

 on the real composition of the mineral. The relative equiva- 

 lents might be so arranged, viz. — 



Atomic Weight. Theory. Experiment. 



Manganese . 28 . . 42*4 . . 45*5 

 Arsenic . . 38 . . 57'6 . . 51'8 



Loss 27 



M n 8 -l A* s 66 100*0 lOO'O 



A Plan for Improving the Carriage Pavement of the Metro- 

 polis. By Lieutenant J. H. Brown, Royal Navy. 



Having observed the unsafe and disgraceful state of the pave- 

 ment of most of our public streets, and, even where Maca- 

 damizing has been adopted, the repairs continually required, 

 and the constant accumulation of mud and dust, I have given 

 the subject much attention for the last few years, and I am 

 induced to propose a plan to remedy the defect. 



I must premise by observing, that the foundations of most 

 of our streets are, of necessity, bad ; as, independent of the 

 nature of the soil, the ground has been so often dug up and 

 turned over, for the purpose of levelling, forming and repairing 

 sewers, laying down gas, water-pipes, &c. &c. ; that although 

 the paving should be executed in the best manner, it is impos- 

 sible that it can remain in the position placed ; for the water, 

 after a glut of rain, passes down between the joints of the 

 stones, the foundation, composed of earth, rubbish, &c. speedily 

 becomes a puddle, softer in some parts than in others, a great 

 portion of which works and churns up between the joints, and 

 allows the stones to sink under the first heavy carriage that 



