78 



SCIENTIFIC NEWS. 



[June 1st, li 



well as the smooth parts. The result is said to be a per- 

 fectly protected piece as long as the lead endures, and good 

 lead is very lasting. 



A Landslip in Dorsetshire. — A correspondent o( Science 

 Gossip gives the following account of a recent landslip 

 near Burton, Bradstock, Dorsetshire. The strata, inferior 

 oolite, consisting of sand intercalated with thin bands 

 of shelly ragstone, resting upon the upper lias, having in 

 all probability been affected by the rains and frosts of an 

 tinusually changeable winter, had slipped away from their 

 intractable base, burying upwards of an acre of the adjacent 

 beach beneath thousands of tons of debris. For a few 

 hours before the sea began to play havoc with the ruins, 

 interesting fossils were to be had in abundance. Many of 

 these were, of course, shattered beyond all hope of re- 

 construction, but countless numbers of them were to be 

 found in more or less perfect states. Among the fossils 

 thus unexpectedly exposed were various genera of the 

 brachiopoda, cephalopoda, conchifera, echinodermata, gas- 

 teropoda, etc., with numerous well-preserved fragments of 

 monocotyledonous wood. 



The Movement of Monuments by Heat. — We are all 

 more or less familiar with many of the important effects 

 produced by the expansion and contraction of metals when 

 subjected to variations of temperature. Special provision 

 for this is made in the fixing of railway metals, and in the 

 construction of bridges, but it is not so generally known or 

 thought of that the movement of towers and monuments 

 from a vertical line is also an effect produced by heat. For 

 instance, the Washington monument leans towards the east 

 in the morning and towards the west in the evening. The 

 dome of the Capitol at Washington moves in the same way, 

 and, by means of a plumb line, it has been ascertained that 

 in the course of a day the movement is eleven and a-half 

 centimetres on each side of the line. A few years ago, a 

 similar effect was noticed on the dome of St. Peter's at 

 Rome, but we read in del ct Tcrre that the movement was 

 then attributed to other causes, although it has since been 

 recognised that the effect is due to the action of heat on 

 the metal of the dome. 



Great Pumps. — At the Engineers' Club, Philadelphia, Mr. 

 H. R. Cornelius read a paper on the two large centrifugal 

 pumps, recently started at the Mare Island Navy Yard, Cali- 

 fornia. These pumps were designed to remove the water 

 from a dock 529 feet long, 122 feet wide, and 36 feet deep, 

 holding about 9,000,000 gallons. The pumps were tested by 

 Government officials, and the following particulars are given 

 in their report : — The performance of these immense 

 machines was almost startling. By watching the water in 

 the dock, it could be seen to lower bodily, and so rapidly that 

 it could be detected by the eye without reference to any 

 fixed point. Through the manhole in the discharge culvert 

 the outflow from the pipes could be seen, and its volume 

 was beyond conception ; it formed a solid prism of water, 

 the full size of the tunnel, projecting far into the river. In 

 55 minutes the water in the dock fell 21 inches, and was 

 pumped out at the rate of 112,922 gallons per minute. At 

 one time the speed of the engines was increased to 160 

 revolutions per minute, and then the discharge was 137,799 

 gallons per minute, almost a river. 



The Lick Observatory Lenses. — We learn from the 

 Sidereal Messenger that these lenses were packed separately 

 in fifteen to twenty thicknesses of soft, clean, cotton cloth ; 

 next came a thick layer of cotton, and then a layer of 

 paper. These packages were then put into wooden boxes 

 lined with felt. No nails were used near the glasses, and 

 the boxes were made the shape of the glasses. These boxes 

 were next enclosed in two others of steel, and packed 



tightly with curled hair. Each steel box was enclosed in 

 another steel box, the insides of which were covered with 

 spiral springs. Both steel boxes were air-tight and water- 

 proof, and the outer chests were packed with asbestos to 

 render them fireproof. Each was then suspended by pivots 

 in strong wooden frames, with contrivances for turning each 

 chest one quarter round every day during the journey to 

 California. This was to prevent any molecular disarrange- 

 ment in the glasses and to avoid the danger of polarization, 

 it being feared that the jarring of the train would disturb 

 the present arrangement of the molecules, unless the 

 position of the glass was changed, and all lines of disturb- 

 ance thus broken up. 



Halation. — When, some seven or eight years since, 

 gelatino-bromide of silver plates rapidly made their way 

 in the studio and field, ousting the long-established wet 

 collodion process, it was remarked by one who had peculiar 

 facilities for forming a judgment upon the work produced 

 by a large number of photographers, that the change of 

 process was marked by a great and general falling off in the 

 quahty of the negatives turned out. No doubt this obser- 

 vation referred more particularly to portrait negatives, but 

 it might have been made with equal justice with regard to 

 landscape negatives. The failing referred to is that which 

 arises from what is known as halation, and is caused by 

 light passing through the film, and being reflected from the 

 back of the plate. This light, being diffused by the translucent 

 but not transparent film, and having to travel after diffusion 

 backwards and forwards through the thickness of the glass, is 

 reflected on to a much larger area than that upon which it 

 originally impinged, with the effect of fogging out all dark 

 shadows that come in close proximity to a bright light. It 

 is impossible to examine the landscape work shown in a 

 photographic exhibition without being struck by the large 

 proportion of productions which are very seriously damaged 

 by halation. — Photographic News. 



Deviations of the Pendulum in Mexico. — During the 

 stay of the French Commission at Fort Loreto, in Puebla, 

 M. Bouquet de la Grye installed, in the chapel of the fort, a 

 seismograph, composed of a pendulum and a multiplying 

 balance. After freeing the observations from abnormal 

 movements, he found that the sun repelled the pendulum in 

 the morning and evening, but that at midday its influence was 

 attractive. The vaults of the chapel, which ran from S.W. 

 to N.E., being heated at morning and evening, thrust the 

 pendulum in a direction opposite to that of the sun ; in the 

 middle of the day the influence was reversed. In grouping 

 the observations under lunar hours, the pendulum was 

 found to be attracted by the moon. The seismograph 

 showed that there were frequent abnormal movements of 

 the pendulum, there being twenty-two oscillations of the 

 ground. The mean movements were in the direction of 

 N.W., S.E., which is the same as that of the chain of the 

 volcano Popocatapetil. While the oscillations were going 

 on, the inhabitants of Puebla felt but a single earthquake 

 shock. It would be interesting to extend these observa- 

 tions, by registering the movements of a long pendulum for 

 a considerable period in an observatory ; they would furnish 

 valuable data respecting the movement of the earth's crust 

 and the tidal phenomena. — Comptes Reitdiis. 



The Transmission of Power. — One of the most in- 

 teresting problems of the present day is how to transmit 

 power from a common centre to distant points at a cheap 

 rate. The tidal forces on our own shores have not hitherto 

 been utilised, yet every one who watches the rush of the 

 tide up our rivers must realise that an enormous amount 

 of energy is always being wasted. The transmission of 

 hydraulic power by mains laid down in the streets is an 



