With such accumulation of sediment and deposit, is it any wonder that sheets are burned? A careful engineer will understand, if the feed water be impure, that he must blow down two or three inches every day, or oftener, that the sediment may be removed as it accumulates, and then an internal examination once in two weeks, or once a month, will insure a clean boiler. Cases of external corrosion, 26--10 dangerous; cases of internal corrosion, 17--5 dangerous; cases of internal grooving, 28--11 dangerous; water gages out of order, 50; blow-out apparatus out of order, 15--7 dangerous; safety valves overloaded, 40--12 dangerous; pressure gages out of order, 54--6 dangerous, varying from -15 to +8 pounds. (We have found several gages entirely ruined from being frozen). Boilers without gages, 4; cases of deficiency of water, 5--1 dangerous; broken braces and stays, 31--7 dangerous; boilers condemned, 2--both dangerous. Two engineers were found drunk on duty, and promptly discharged. There were 9 serious explosions during the month, by which 99 persons were killed, and 6 wounded. Eighty-seven of the killed were passengers on the ill-fated steamer _H.R. Arthur_, on the Mississippi River. Many were drowned, and some burned, but the origin of the calamity was the bad quality of the boilers, which a careless management was unable to detect. The upper and fore part of the boat was blown away by the exploded boilers, and, to add to the horror, what remained took fire. None of these exploded boilers were under the care of this company. * * * * * Five ore-roasting furnaces are in full blast in Nevada. * * * * * IMPROVED COMPOUND SPIRAL CAR SPRING FOR RAILWAY CARRIAGES. Our engravings illustrate an improved compound car-spring, which appears to possess all the requisites of a first-class spring, combining in its construction extreme simplicity with great strength, and a feature whereby the power of the spring increases with increase of the load, and _vice versa_, so that its flexibility remains nearly constant for all loads. Fig. 1 is a perspective view of this spring, with a portion of the side of the case broken out to show the interior arrangement of the spiral springs. Fig. 2 is a section of the compressing plate. Fig. 3 is a plan view, showing the arrangement of the tubes which enclose the springs. [Illustration: POTT'S' SPIRAL CAR SPRING FOR RAILWAY CARRIAGES. _Fig. 1 Fig. 2 Fig. 3_] The case is cast in two pieces. Its vertical wall is cast in a single piece, and has at the top a flange or bead extending inwardly, against which the compressing plate abuts when the spring is not compressed, as shown in Fig. 2. A bottom plate completes the case.