โ Scribed by C.
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Frank. Inst.,
represents this portion broken off and swinging around at a right angle to its proper position. This cord ipasses over the shrive k, and extends down to within a convenient distance of the floor, and has attached to its extremity the pan l, for holding the weight shown in Fig. 8. Care must be taken that the distance of the shrive k, from the crossbar h, and also from the bottom of the scale pan to the floor, is as great as the proposed rise and fall of the holder. The arrangement of cords, shrives, etc., will be readily seen in the perspective view, ;Fig. 4.
The pipe for the admission and exit of the "gas, is shown as passing through the side of the wooden tank, and rising near the centre to within a few inches of the top of the holder.
The manner of using is as follows : The cock o, in the inlet pipe, being open to the atmosphere, water is admitted to the tank until it rises to the top of the pipe. Weights (Fig. 3) are placed on scale pan l, in sufficient amount to overbalance the weight of the holder, and to overcome the friction of the cords and pulleys, when the cock o should be closed. Communication being opened between the inlet pipe and the source of gas supply, the gas enters, and the holder rises until filled. The supply of gas should then be cut off, the weights removed from the pan l, the space at the top of holder filled with water, and the gas is ready for use, under the necessary pressure. When the holder is exhausted, the water on top is run off by means of an india-rubber tube, acting as a siphon, the weights replaced on the pan, and the holder is ready for refi!!ing.
Where the oxy-hydrogen light is much used, holder~ are almost indispensable, and in all cases they effect a large saving of time and material in the preparation and use of the gases. K.
Sun-Spots and Magnetism.--Prof. Wolf finds, by applying his formula for the relation between sun-spots and magnetism, a calculated value of 6'40 p for the mean variation of declination at Prague. The observed value was 6'47', an agreement which he justly regards as marvelous. He believes the mean sun-spot period to be 11~ years, but there are strong indications of a grand period of 178 years, embracing 16 solar periods of 11~-years, and 15 revolutions of Jupiter.
๐ SIMILAR VOLUMES
Chili Saltpetre.--Nitrate of soda is found in great abundance ]n the desert of Atacama. Under a bed of soil, varying in thickness from 10 to 50 centilnetres (3"937 to 19"685 in.), there is a compact layer of gypsum, under which the salpetre is found in irregular beds, with a thickness sometimes reac
Work of Diffusion.
Peckeliih and Washington, obtaining for the epoch of ininimum 1878"9. The variations in m~tgnetic declination at Milan, Vienna, Prague, Munich and Christiania indic tte the minimum epoch ]878"5. Both results agree in pointing to an epoch of 11"7 years.~Compt. Read. C.