December 24, 1886.] 



SCIENCE. 



583 



and deepens the original sense-impression. Dr. 

 Holbrook gives wholesome advice to persons of 

 weak memories, and shows how such may be 

 trained to become very retentive and accurate. 

 A few judicious paragraphs are given on the art 

 of forgetting, instruction in which is quite as 

 necessary for that class of persons who insist on 

 overloading their memories with all sorts of 

 mental rubbish, as is instruction in remembering 

 for those minds which seem to retain nothing. 



LONDON LETTER. 



An interesting discovery has very recently been 

 made in the direct line between Pompeii and 

 Nocera. The digging of a well in a vineyard re- 

 vealed the existence of a street of tombs, about 

 one thousand feet east of the amphitheatre of 

 Pompeii. If the whole street is as closely lined 

 veith tombs as is the portion laid bare, it will be 

 one of the most important discoveries lately made 

 in that part of the world ; but unfortunately 

 money is wanting, so that the excavation is going 

 on very slowly. Most of the tombs are covered 

 with rude inscriptions painted in red, many of 

 them being of the nature of advertisements, the 

 tombs thus serving the purpose of a newspaper 

 along the much -frequented road. The exact date 

 has not yet been accurately ascertained, but they 

 probably belong to the periods of Julius Caesar 

 and Tiberius. A contrast may be drawn between 

 the condition of Pompeii and that of Pergamon, 

 v^hich, although double the size of Pompeii, has, 

 thanks to the energy of the Prussian government, 

 been laid clear within eight years. In the latter, 

 beautiful, finely painted ?tatues, votive offerings 

 to Athena, and belonging to the sixth century 

 B.C., have been found buried in the earth, and 

 Hterally forming the foundation of the houses 

 above. Their style of art is one hitherto not sup- 

 posed possible at so remote a period, and they 

 cause Pompeii to appear quite modern. 



The discovery of an aqueduct which probably 

 dates back to the time of King Solomon is re- 

 ported from Jerusalem, and it is confidently an- 

 ticipated that the further excavation of it wiU 

 bring to light some extremely interesting and 

 valuable inscriptions. 



The following particulars with regard to the 

 Severn tunnel, which shortens the distance be- 

 tween the South Wales coal-field and the south 

 and vrest of England, and which was opened 

 yesterday for passenger traffic, may be of interest. 

 The first sod was turned in March, 1873. The 

 length of the tunnel is 7,664 yards, or 4i miles, of 

 which 3J miles are under the river-bed, with a 

 minimum ' cover ' of 45 feet, and a maximum of 



100 ; all this portion being bored through hard 

 sandstone, conglomerate, and red marl, and cost- 

 ing roughly £100 per yard. The works have been 

 flooded by land-springs four times, and the total 

 cost is about two millions sterling. The tunnel 

 is lined throughout with vitrified brick, set in 

 about three feet thickness of cement. 



It is announced to-day that Professor Rticker, 

 F.R.S., has been appointed by the lord president 

 of the council to the professorship of physics in 

 the Normal school of science, and Royal school of 

 mines. South Kensington, London, made vacant 

 by the death of Professor Guthrie, F.R.S. The 

 friends of the latter will regret to learn that his 

 widow and family are but ill provided for, in con- 

 sequence of the numerous family claims upon 

 him during his life, and it is probable that the 

 Physical society of London will start a fund on 

 their behalf. Professor Rticker was, until re- 

 cently, professor of physics at the Yorkshire col- 

 lege, Leeds, after which he unsuccessfully con- 

 tested a parliamentary election for that city. 



The reading and discussion of Mr. Gisbert 

 Kapp's paper on the ' Predetermination of dyna- 

 mo characteristics' have occupied three evenings 

 (one a special and extra meeting) at the Society of 

 telegraph engineers and electricians. The paper 

 dealt with the construction beforehand of what 

 may be called the ' idle ' characteristic curve of 

 dynamos ; and the discussion turned in great part 

 upon the questions of magnetic resistance, and 

 especially of air resistance, as well as on the anal- 

 ogy between the electric and magnetic circuits. 

 Before commencing his paper, Mr. Kapp stated 

 that only two days previously he had found that 

 many of his points had been anticipated in a pa- 

 per on dynamo-electric machinery, by Dr. J. and 

 Dr. E. Hopkinson, communicated to the Royal 

 society in May last, but which had only just been 

 published. It is greatly to be regretted that the 

 routine of the Royal society prevents an earlier 

 publication of important scientific papers which 

 have a direct bearing upon industrial progress. 



One result of the more extended adoption of 

 the electric light in public buildings in London is 

 a notable increase in the number of winter exhi- 

 bitions of pictures. Nearly all artistic societies of 

 any importance now hold their ' winter exhibi- 

 tions ' with as great regularity as the summer 

 ones, which open in May. The electric lighting 

 of the Grosvenor gallery, due chiefly to Sir Coutts 

 Lindsay, first demonstrated the advantages which 

 were thus obtainable. 



The disinfection of articles of clothing, and of 

 dwellings, after infectious ailments, is admittedly 

 one of the most important duties which attends 

 the work of preventing disease. A recent report 



