PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 573 



Mis o^ slag which surround old established iron-works. It is said 

 that this refuse material may be substituted for emery, and that it 

 is even superior to emery for polishing steel, iron, copper and 

 other metals. The new substance is called "metalline," andean 

 be produced at seventy or eighty per cent less cost than emery. — 

 The American Journal of Mining. 



A Kerosene Telegraph. 



An apparatus termed a " kerosene telegraph " has been invented 

 in Boston. It consists of two small boxes, arranged with levers 

 for opening and closing apertures of an inch and a half in diame- 

 ter. An ordinary kerosene lamp was placed in each box with a 

 reflector behind it. One of these machines was taken by Mr. Cy- 

 rus A. George (also connected with the oiEce), to a point in East 

 Cambridge, a mile and a half distant from the city hall, and at 

 eight and a half o'clock (the time previously agreed upon), hia 

 signals were received by his brother, who was stationed in the 

 fire-alarm office in the cupola of the city hall. He answered them, 

 and they continued to converse with great ease and rapidity for 

 an hour, sending and receiving messages. They found no diffi- 

 culty in reading as accurately and nearly as fast as by the ordinary 

 means of telegraphing. With this apparatus the inventor believes 

 he could operate easily five miles in clear weather, and by increas- 

 ing the power of the light, ten or fifteen miles. An experiment 

 will soon be made from the Boston office with some distant point 

 in Koxbury or Dorchester. 



Meteorology. 



The Moniteur has published a few remarks by M. Houzeau, well 

 known for his studies on ozone, concerning the anomalous weather 

 in France during the whole of this summer. He says: 



Ozone, the principle to which the atmosphere owes the chem- 

 ical activity it manifests on iodized test-paper made with vinous 

 litmus and starch, exists normally in the country air of our tem- 

 perate climates. Several causes fiivor the manifestation of the 

 active properties of air; these are chiefly the winds and aqueous 

 vapor, although, in reality, neither of them, taken separately, acte 

 directly on the test-paper so as to change it to blue. When, not- 

 withstanding the violence of the wind, iodide of potassium is not 

 very perceptibly aflfected, it may be inferred that the atmosphere 

 does not contain a sufficient dose of moisture to allow of the devel- 



