Those who wonder whether wireless telegraphy is really practical should notice what Gen. Greeley, chief of the army signal service, has to say on the subject. He is enthusiastic over the success attending the installation of a wireless system in Alaska. Hundreds of messages are being transmitted daily between Cape Nome and St Michael, a distance of 160 miles across Norton Sound. "Very little has been said about it in the public press, " writes Gen. Greeley, "but are demonstrating every hour of the day up in Alaska that a practical, working wireless telegraph system is possible. Our system has been operated there for more than a year, and with most complete success. Thousands of messages have been transmitted between the two points, and not only the private citizens but the government officials of that neighborhood are now largely dependent upon it. It is no longer an experiment. It is used for commercial purposes as well as for government business.

J. L. Haycock, Canadian inspector of binder twine, gives the following simple rule for determining the length of twine in a ball: "Take a sample ball, press the strands close together, and note the number required lying side by side to make an inch. Every strand within the inch will represent 50 feet in the pound. If ten strands lying side by side makes 1 in., then a pound will contain 600 feet; if eleven strands, 550 feet; if twelve strands, 600 feet, and so on. Having this rule in mind, anyone can test his twine for length, and need not be duped by short measure. "

The Dominion Iron and Steel Company has, it is understood, decided to adopt at its works at Sydney, Nova Scotia, a new and inexpensive process for the manufacture of pig iron, utilizing waste iron ore, which costs from 60 to 75 cents a ton. Iron ore in this condition can be used only when it is solidified For a great many years chemists endeavored to solve this problem, but it was only a few years ago that W. Owen, consulting engineer and foreign representative of Bruck, Kretschel & Co., steel manufacturers, of Osnabruck, Germany, made the discovery. Since then the process has been adopted by seven German and two or three English steel companies, with eminent satisfaction. The waste is solidified, usually in bricks, and in this condition is placed in blast furnaces, when pig is produced. The plant which the Sydney Steel Company proposes to install will cost about $8000, and will have a daily output of about 75 tons. It will be the first of the kind erected on the continent, and the company will have exclusive use for the Dominion of Canada.

A radium clock which will keep time indefinitely has been constructed by Harrison Martindale, of England. The clock comprises a small tube in which is placed a minute quantity of radium supported in an exhausted glass vessel by a quartz rod. To the lower end of the tube, which is colored violet by the action of the radium, an electroscope formed of two long leaves or strips of silver is attached. A charge of electricity in which there are no beta rays is transmitted through the activity of the radium into the leaves, and the latter thereby expand until they touch the sides of the vessel. connected to earth by wires, which instantly conduct the electric charge, and the leaves fall together. This simple operation is repeated incessantly every two minutes until the radium is exhausted, which in this instance it is computed will occupy 30,000 years.