132 KANSAS CITY REVIEW OF SCIENCE. 
iron surface very much greater than the ordinary or normal pressure, often to the 
extent of explosion. 
The experiments by the commission have tended in all respects to sustain 
this theory, as boilers were exploded at pressures far below what they had pre- 
viously withstood without injury, by providing means by which the steam was 
suddenly removed from the steam-space in the boiler. Some difference existed 
in the commission as to whether the trials did not exaggerate the conditions be- 
yond what would be in the practical use of boilers, but the weight of opinion was 
contrary and the report of all the members was decidedly in favor of the correct- 
ness of Mr. Lawson's theory, and there seems to be no doubt of its great value 
in boiler construction for the future. The remedy he suggests, is an arched dia- 
phragm fixed horizontally in the boiler near the water line and supplied with 
valves under the control of the engineer; the object being to retard the time of 
passage of steam from the water-compartment, thus preventing the instantaneous 
removal of the pressure from the water. This idea also received the approval of 
the commission. 
Considerable attention has been bestowed in the large cities of the country 
upon what has been considered in some respects an experiment — the cable system 
of operating street cars. While in San Francisco, last summer, that city being 
the birth-place of the experiment, I found no doubt expressed as to their com- 
plete success there. But they are only employed on the steep grades of the hills 
of that city, and the question as to their economy on level streets had not been 
tested. A line, however, has been in operation in Chicago, which has been so 
satisfactory that it has been very much extended, and a similar roadway has been 
put down in Philadelphia. As you all know, Kansas City has granted a charter, 
and the prospects are that our bluff barrier will soon be overcome by this method. 
It seems to be peculiarly adapted, as in San Francisco, to our broken topography 
and heavy grades on east and west lines. 
In railway building the aggregate of new road for the year is over 11,000 
miles, an increase of more than 3,000 miles over the preceding year. But it 
may be considered the maximum year, as the prospect for 1883 promises a very 
marked reduction in railway building. But the indications are favorable for 
a larger mileage of new road for Kansas City than in some years past. 
In iron and coal the product has been very large. The year 1881 was nota- 
ble for the highest figures ever reached in these great factors of industry, and the 
past year falls but little below. There are evidences, however, that cannot be 
mistaken that the production has been beyond the demands of consumption, and 
a very decided diminution may be expected for the present year. 
In the precious metals there has been a decrease in the value of the mine 
product, which, however, is nominal. Of gold our mines produced $31,500,000, 
and of silver $44,700,000; a decline of $5,000,000 in gold, and an increase of 
$2,600,000 in silver. 
Beet sugar has been sucessfuUy produced in California, at the Alvarado 
factory, a most important fact, and it is confidently claimed that the difficulties 
