July 20, 1 888.] 



SCIENTIFIC NEWS. 



7i 



FECUNDITY OF SPARROWS. 

 Your correspondent, Mr. J. P. Nunn, states in his letter 

 (Scientific News, II. p. 21) some very interesting facts 

 concerning sparrows, but, unless these birds are remarkably 

 prolific, I should like to know why they so far outnumber all 

 our other species of land-birds. Sigma. 



RECENT INVENTIONS. 



The following list has been compiled especially for the Scientific 

 News bv Messrs. "W. P. Thompson and Boult, Patent Agents, oj 

 323, High Holborn, London, W.C ; Newcastle Chambers, Angel 

 Row, Nottingham; Ducie Buildings, Bank Street, Manchester ; 

 and 6, Lord Street, Liverpool. 



Producing Currents of Air. — A fanning apparatus 

 has been patented by Mr. A. J. Boult, on behalf of F. 

 Bisson. The apparatus consists of a rotary fan mounted 

 in bearings; on the axis of the fan a small pinion 

 wheel gears with a wheel of larger dimensions, and has a 

 rotary motion imparted to it in each direction alter- 

 nately ; the motion in one direction being produced 

 through a cord mechanism by the person using it, and 

 in the other by a suitable weight or spring. 



Milk-pan. — A milk-pan has been patented by Mr. J. 

 Llewellin. The pan is constructed of a shallow recep- 

 tacle, having hollow walls in two parts, the bottom of 

 which are dish-shaped. The space between the two 

 parts receives hot or cold water, to regulate the tempera- 

 ture of the milk, which is placed in the inner portion, 

 thereby causing the cream to rise. The water is 

 introduced through an opening having a cover, and the 

 pan has a tap in the middle of the bottom to allow the 

 water to be drawn off. 



Anemometers. — An anemometer has been patented 

 by Mr. J. Hicks. The object is to substitute metal 

 pressure chambers in place of those usually used. A disc 

 of metal is mounted on a suitably shaped chuck, and has 

 spun upon it a number of concentric annular corruga- 

 tions, the centre of the disc being formed with a tubu- 

 lar neck on one side, and its edge with a rim on the 

 other side. Two of these discs are placed face to face, 

 with the rim of the one within the rim ot the other, and 

 are soldered thus air-tight, thereby forming one section of 

 the pressure chamber ; any suitable number of these 

 sections are connected together by the necks, which are 

 placed one within the other, and spun over one another, 

 and soldered air-tight. When required to indicate 

 vacuum, the corrugated discs are made with convex 

 outer faces and when for pressure they are made with 

 concave outer faces. The interiors are protected by 

 coating with india-rubber varnish and the exteriors with 

 stove jet. 



Transforming Electric Currents. — Mr. A. J. Boult 

 has patented on behalf of S. Doubrava an apparatus for 

 transforming electric currents. The invention is com- 

 posed of a commutator consisting oi a metal disc, 

 revolving round a shaft. To the periphery of the disc are 

 fastened insulating strips, and two contact brushes are 

 so arranged that when one touches an insulating strip, 

 the other touches the conducting part of the periphery. 

 This commutator charges a condenser and discharges it 

 afterwards into- the circuit through a larger condenser. 

 When the disc revolves, the second coating of the 



smaller condenser is connected with the generator by 

 means of one of the brushes, the disc, and a sliding 

 contact, and this coating is charged to the potential of the 

 generator ; by a further movement of the disc, this 

 connection is broken, and the large condenser is connected 

 by means of the other brush. By this means the smaller 

 condenser is discharged into the larger one, through this 

 into the circuit, and by the combination of these two 

 condensers the potential will be lowered. By the 

 combination of the condensers the high tension 01 the 

 generator is changed into a lower one in proportion to 

 the relative surfaces of the condensers. 



Compass. — Mr. A. Gross has patented a compass for 

 indicating when a vessel leaves its course. A hollow 

 axle is fixed in the centre of the compass glass, and a 

 forked piece of brass acting as a course setter is fitted 

 thereon on the outside of the glass, with its ends resting 

 on the rim of the compass. The axle is carried below 

 the glass to within an inch of the compass card, and on 

 its lower end is fitted another transmission fork. The 

 ends of this fork are made of fine gold wires, fixed to 

 have an outward spring and to reach the periphery of 

 the card. The wires pass through the grooves of a slide 

 and the perimeter ends are brought together or set 

 apart by means of the slide operated by a pinion gear 

 passing through the hollow axle, and having a racket 

 adjustment fixed to it parallel with the glass. A piece 

 of platinum wire is fixed at the north point of the com- 

 pass connected with the magnetised bar of the card ; this 

 wire is bent to give spring power with the end pointing 

 to the glass. The cap of the card is made of tempered 

 silver steel. The wires of a batter}' are so connected 

 with the compass bowl and alarm, that when either of the 

 wires of the lower fork comes in contact with the plati- 

 num wire at the north point the circuit is complete. 

 The wires of the lower fork limit the extent of deviation, 

 so that when such deviation occurs the wires come into 

 contact, and sound the alarm. 



Switch. — A " bell pull " electric-light switch has been 

 patented by Mr. A. P. Lundberg. The object is to pro- 

 duce a switch which will make good contact, and quickly 

 " make " or " break " contact, and which, with every 

 fresh pull, will make and break contact alternately. A 

 disc is mounted on a base of any insulating material, 

 so as to be free to rotate on a centre. Two metallic 

 terminals, also on the base and rubbing against the cir- 

 cumference of the disc, are so arranged that every alter- 

 nate quarter of a revolution of the disc causes metallic 

 contact to be made or broken. The revolving disc has 

 on its underside four pins fixed equidistant from one 

 another in a circle. Attached to the bases under the disc 

 and pins is a bar, free to move vertically, having on its 

 upper side a spring catch passing freely with the bar in 

 a downward direction without disturbing the disc, but 

 which engages with one of the four pins, when moving 

 upwards, thus carrying the disc round a quarter of a 

 revolution. The movement of the bar downwards and 

 upwards will again move the disc through another 

 quarter of a revolution by means of the spring catch 

 engaging with the next of the four pins, and so, by con- 

 tinually rotating'the disc, alternately making and break- 

 ing the contact. The bar has attached to it a spring 

 which, left to itself, holds the bar in a fixed position, so 

 that after being pulled down it returns to that position. 



