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THE SUNSHINE RECORDER.

McLeod’s sunshine recorder consists of a camera fixed with its axis parallel to that of the earth, and with the lens northward.  Opposite to the lens there is placed a round-bottomed flask, silvered inside.  The solar rays reflected from this sphere pass through the lens, and act on the sensitive surface.

[Illustration]

The construction of the instrument is illustrated by the subjoined cut, A being a camera supported at an inclination of 56 degrees with the horizon, and B the spherical flask silvered inside, while at D is placed the ferro-prussiate paper destined to receive the solar impression.  The dotted line, C, may represent the direction of the central solar ray at one particular time, and it is easy to see how the sunlight reflected from the flask always passes through the lens.  As the sun moves (apparently) in a circle round the flask, the image formed by the lens moves round on the sensitive paper, forming an arc of a circle.

Although it is obvious that any sensitive surface might be used in the McLeod sunshine recorder, the inventor prefers at present to use the ordinary ferro-prussiate paper as employed by engineers for copying tracings, as this paper can be kept for a considerable length of time without change, and the blue image is fixed by mere washing in water; another advantage is the circumstance that a scale or set of datum lines can be readily printed on the paper from an engraved block, and if the printed papers be made to register properly in the camera, the records obtained will show at a glance the time at which sunshine commenced and ceased.

Instead of specially silvering a flask inside, it will be found convenient to make use of one of the silvered globes which are sold as Christmas tree ornaments.

The sensitive fluid for preparing the ferro-prussiate paper is made as follows:  One part by weight of ferricyanide of potassium (red prussiate) is dissolved in eight parts of water, and one part of ammonia-citrate of iron is added.  This last addition must be made in the dark-room.  A smooth-faced paper is now floated on the liquid and allowed to dry.—­Photo.  News.

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BREAKING OF A WATER MAIN.

In Boston, Mass., recently, at a point where two iron bridges, with stone abutments, are being built over the Boston and Albany Railroad tracks at Brookline Avenue, the main water pipe, which partially supplies the city with water, had to be raised, and while in that position a large stone which was being raised slipped upon the pipe and broke it.  Immediately a stream of water fifteen feet high spurted out.  Before the water could be shut off it had made a breach thirty feet long in the main line of track, so that the entire four tracks, sleepers, and roadbed at that point were washed completely away.