TRANSACTIONS OF SECTION I. 817 



complete combustion, such as carbonic oxide or sulphuretted hydrogen. He also 

 discussed the effects of white-damp, and drew attention to the exceedingly poisonous 

 character of the gases from the explosion of blasting powder. 



In conclusion he described and exhibited a portable apparatus for enabling 

 miners to escape through an atmosphere of after-damp to the fresh air in the 

 2ieighbourhood of the shafts, and for rescue purposes. 



5. Observations on the Effects of After-damp. 

 By J. Shaw Lyttle, M.D. 



The writer gave a detailed account of the symptoms presented by those who 

 were found alive after the recent explosion at the Albion Steam Colliery. 



6. Experiments on Memory. By W. G. Smith, 31. A., Ph.D. 



If we examine any case of ready and accurate recollection taken from our daily 

 experience, we find it difficult, if not impossible, to say how much of this accuracy 

 is due to such factors as the interest which the experience aroused, the attention 

 which we paid to it, the amount of effort and time spent during the experience. 

 The following experiments were carried out with the view of trying to isolate 

 experimentally the process of attention, and showing what changes in recollection 

 occur when various kinds of distraction of attention are introduced. The experi- 

 ments were begun in the Institute for Experimental Psychology in Leipzig, and 

 have been carried on in the Physiological Laboratory in Oxford. 



After a considerable number of preliminary experiments had been made, the 

 following method was adopted. Twelve letters of the alphabet, arranged in such 

 a manner that intelligible words or interesting ideas should not readily be sug- 

 gested, were written upon a card, so as to form three lines. The card was shown 

 to the reagent, who then tried to learn what was written on it. In each new 

 experiment a new combination of letters was employed. By making a sufficiently 

 large number of observations with different persons, one can eliminate to a con- 

 siderable extent the fallacies arising from varying difficulty or familiarity of the 

 combinations employed. The card was shown in every case for ten seconds, and 

 the reagent was required, either immediately after he ceased to see the card or after 

 an interval of about two seconds, to reproduce as much as he could remember of 

 what he had seen. 



A distinct and at the same time fairly simple form of distraction was secured 

 by making the reagent repeat the series 2, 4, 6, 8 . . . , or more rarely 3, 6, 9 ... , 

 while he was learning the letters on the card. In order that the person in charge 

 of the experiments might have an effective control over the activity of the reagent, 

 the series had to be repeated aloud, and each step in the addition was made to 

 coincide with the stroke of a metronome going at the rate of sixty to seventy beats 

 per minute. In order to compare the results of this form of distraction with those 

 gained where the vocal organ was employed, but the mental effort involved was 

 very small, the reagent was next required while memorising to repeat aloud with 

 each beat of the nietronome an unintelligible syllable, e.g., ' la.' This form of 

 distraction was further compared with that caused by activity of another set of 

 muscles, viz., those employed in tapping the table with the forefinger, each tap 

 coinciding with a beat of the metronome. Lastly, experiments were carried out 

 to show the effect of memorising without any distraction save that due to the fact 

 that the metronome continued to beat. These four variations were given in varying 

 order one after the other, and were so arranged that 8, 12, IG, or 20 experiments 

 were made in one hour. 



In calculating the value of the results two methods were applied. The first 

 reeembles that employed by Miinsterberg ('Beitriigo zur experimentellen Psycho- 

 logie'), and consists in summing up the errors committed in reproducing the 

 letters written on the card. The errors were classified as follows: — (1) Omission 

 of a letter ; (2) insertion of a wrong letter ; (3) displacement of a letter or repro- 

 1894. 3 G 



