May 7, 1891] 



NATURE 



21 



The calculated calorific value is 14,830 thermal units per 

 pound, which corresponds to the evaporation of 15 35 pounds of 

 water from and at 212° F. A portion of the coal used was also 

 tested by a Thomson calorimeter, and gave a value of 14,980 

 thermal units per pound. Thirteen samples of furnace gases 

 were taken over mercury and were analyzed. The following 

 are the means : — 



By volume By weight 



percent. percent. 



Carbonic acid 8'20 ... I2'I2 



Carbonic oxide o'oo ... 000 



Oxygen 1117 ... 1201 



Nitrogen 8063 ... 75"87 



Chimney temperatures were read every half-hour by a mercury 

 thermometer and by two Murrie pyrometers at 30 feet above the 

 furnace bars. The readings of the three instruments agreed, 

 the average temperature bemg 452° F. It was a pity that the 

 readings were taken so far from the fires, it being desirable to 

 know the heat of the products of combustion immediately after 

 leaving the heating surface of the boiler. The arrangement, 

 however, was unavoidable, owing to the exigencies of running 

 the ship on her voyage. The measurement of the feed was 

 carried out by means of two tanks in the usual way. An effort 

 was made to determine the quantity of water brought over un- 

 evaporated, by the draught of steam. This was done by taking 

 samples of condensed steam from the steam pipe and samples of 

 boiler water, and analyzing them to ascertain the percentage of 

 salt. Unforlunalely the apparatus broke down ; but from two 

 pairs of analyses ma le, it was estimated that there was 2 87 per 

 cent, of unevaporated boiler water in the condensed steam. If 

 this were the case with boilers so easily driven as those of the 

 lona, where there could hardly have been any semblance of 

 "priming," as the term is understood by engineers, the quantity 

 of water brought over in small and hardly driven boilers must 

 be enormous. It is a point of the greatest importance in steam- 

 engine economy, and we trust Prof. Kennedy will pursue his 

 investigations in this direction. It also came out during the 

 discussion that the stop valve, or throttle valve, was very much 

 closed during the trial, a fact which should still further have 

 reduced the chance of unevaporated water finding its way into 

 the engines. 



Indicator diagrams were taken every half-hour during the 

 trial, and an average set is attached to the report. The power 

 was very evenly distributed between the three cylinders, showing 

 good design of the engines. The total indicated horse-power 

 was 645 -4. Diagrams were also taken from the air and circu- 

 lating pumps. For these interesting and valuable details we 

 must refer our readers to the paper itself, as we are unable to 

 reproduce the diagrams. 



The following are some of the chief elements of the trial : — 



July 13 and 14, 1890. 

 16 hours. 

 3160 square feet. 

 2590 ,, 

 42 „ 

 75 '2 ratio. 



2-3 ,. 

 165 'O lbs. per sq. in. 



1425 



13-88 „ 

 611 

 205-6 



221*2 

 2186 



942 pounds. 

 22-4 



0*298 ,, 

 "■46 ,, 



I "02 ,, 

 86160 



10 63 „ 



Date 



Duration of trial 

 Heating surface, total ... 



,, ,, tubes 



Grate area 



Total heating surface to grate surface... 

 Grate area to flue area through tubes... 

 Mean boiler pressure above atmosphere 

 Mean admission pressure, high-pressure 



cylinder 



Mean vacuum in condenser below at- 

 mosphere 



Mean revolutions per minute 



I.H.P. of high-pressure cylinder 

 ,, intermediate ,, 



„ low-pressure ,, 



Coal burnt per hour 



,, ,, square foot of grate per 



hour 



Coal burnt per square foot of total 



heating-surface per hour 



Coal burnt per I.H.P. per hour 

 Carbon equivalent of coal ... ... 



Feed- water per hour 



„ ,, lb. of coal 



M ,, ,, from and at 

 212° F 



NO. I 123, VOL. 44] 



Efficiency of boiler 69*2 percent. 



,, engine ... ... ... 171 ,, 



,, engine and boiler ... ii'8 ,, 



Mean speed of vessel during trial ... 8 "6 knots per hour. 



A long discussion, occupying both evenings of the meeting, 

 followed the reading of the paper, but our account has already 

 extended to such a length that we cannot give a report of it. 

 Perhaps the most interesting point raised was in connection with 

 the closing of the chimney damper, which it appeared was only 

 one-sixth open during the trial. The reason givtn for this was 

 that in this way heat was prevented from escaping up the 

 chimney. It is difficult to account for such an effect, excepting 

 perhaps to some trifling extent due to minor causes, but several 

 engineers whose opinion is worthy of resptct testified that such 

 was the effect in practice. One would think that the escape of 

 heat by the chimney would be governed by the volume of 

 escaping products of combustion with a chimney of any reasonable 

 cross area. 



UNIVERSITY AND ED UCA TIONAL 

 INTELLIGENCE. 



Cambridge. — The first Clerk Maxwell Scholarship, for re- 

 search in Experimental Physics, has been awarded to W. 

 Cassie, M.A., Trinity College. 



Mr. H. J. Mackinder, the Reader in Geography at Oxford, is 

 to lecture for the Teachers' Training Syndicate on " The Teach- 

 ing of Geography," on May 30. 



The annual dinner of the Philosophical Society was held in 

 the Combination Room of St. John's College on May 2, Prof. 

 G. Darwin in the chair. 



Dublin. — Sir Robert Ball begins on Wednesday, the 13th 

 inst., a course of lectures on "The Theory of Screws," in 

 Trinity College, Dublin. 



SCIENTIFIC SERIALS. 

 The Quarterly Journal of Microscopical Science for March 

 contains : — On a new species of Phymosoma, with a synopsis 

 of the genus, and some account of its geographical distribution, 

 by Arthur E. Shipley (Plate .xi.). The new species, P. iveldoni, 

 was found by Prof. Weldon at Bimini Island, the Bahamas ; it 

 has no trace of hooks on the introvert ; there are two retractors. 

 A synopsis of the twenty-seven species now known is given, 

 but seventeen species are described in Selenka's monograph on 

 the Sipunculidse. As to the geographical distribution, seventeen 

 species are found in the Malay Archipelago, of which thirteen 

 are endemic, five are found in the Red Sea, four in the Mauri 

 tius, and three are found in the West Indies, but P. lovenii is 

 found only in the Hergen Fiord. — On the British species of 

 Crisia, by Sidney F. Harmer (Plate xii.). The author thinks 

 that the ovicells furnish satisfactory specific characters ; the 

 aperture in the ovicell is also an important character. Specific 

 diagnoses of C. denticulata, Lmk., C. eburnca, Linn., C. 

 aculeata, Hass., and C. ramosa, n. sp., are given. Notes 

 are given of the habit of the Zoarium at different seasons, on 

 the mode of branching, and on the breeding-times. — The later 

 larval development of Amphioxus, by Arthur Willey (Plates 

 xiii.-xv ). The author again visited Messina, in the summer of 

 1890, to complete his studies on the development of the atrial 

 chamber of Amphioxus. As a possible explanation of the 

 asymmetry of the larva, Willey thinks that it can be traced 

 ultimately to the adaptive forward extension of the notochord, 

 being thus a purely ontogenetic phenomenon ; the club-shaped 

 gland is shown to be a modified gill-slit. — On the structure of 

 two new genera of earthworms belonging to the Eudrilidae, and 

 some remarks on Nemertodrilus, by Frank E. Beddard (Plates 

 xvi.-xx.). Hyperiodrilus africanus, n. gen. and sp., and Helio- 

 drilus lagosensis, n. gen. and sp., found in a Ward case from 

 Lagos, at Kew Gardens. 



The only article of general interest in the Nuovo Giornale 

 Botaniio Italiano for April is a note on the stigmatic disk of 

 Vinca major, by Sig. M. Pitzorno. In the reports of the 

 Italian Botanical Society are short papers by Sig. Baccarini on 

 the secretory system of the Papilionaceae ; on the arrangement 

 of herbaria, by Sig. L. Micheletti ; and others of special interest 

 to Italian botanists. 



