﻿Otago Institute. 421 



science analytical geometry, in which, by the use of symbols, the reasoning is 

 carried on independent to a great extent of the ideas of the magnitudes them- 

 selves." 



2. " Notes upon the Experiments on the so-called Psychic Force recently 

 made by Mr. Crookes,"* by J. S. Webb. 



(abstract.) 



In this paper the author said that he would not offer any arguments for or 

 against the theories of professed spiritualism. The subject was one of which, 

 so far as regards its more recent manifestations, he knew nothing. He claimed 

 that Mr. Crookes had not made enough experiments, nor taken sufficient care 

 in them, to establish his deduction that a hitherto unknown natural force had 

 been discovered. He then criticised the experiments in detail, showing, 

 firstly, that no attempt had been made to verify the experiments, or ascertaia 

 the "personal error" of the observers; secondly, that the circumstances of the 

 experiments were not accurately remarked, and that they were annoy ingly 

 fantastic and wanting in precision ; thirdly, with reference to the instrument 

 used in the second experiment, the author states that "the dimensions of 

 the mahogany board used in this case are carefully given by Mr. Crookes, and 

 he informs us that when the apparatus was adjusted before the experiment 

 began, that portion of its weight which afiected the spring balance was 3Bjs. 

 [Description quoted.] Now, the specific gravity of mahogany, as ordinaiily 

 given in the tables, is 1060 (that of water being taken at 1000) and irrespec- 

 tive of that portion of the board which absolutely rested upon the table, we 

 have in this case 342 cubic inches of mahogany suspended, one-half of the 

 weight of which would, if the board were truly horizontal, have rested upon 

 the balance. A cubic foot of water weighs rather more than 997ozs. avoirdu- 

 pois, hence 342 cubic inches of mahogany, at the specific gravity just stated, 

 weigh rather more than 209ozs., or 13]1)S. loz. It is strange that a trained 

 man of science should not have noticed this discrepancy. At the very least 

 we might have expected that he woiild have assured himself of the absence of 

 all suspicious circumstances by weighing the whole board before adjustment, 

 since it was the efiect of the so-called Psychic Force upon its apparent weight, 

 which he had set himself to observe. It may be answered that mahoganies 

 vary much in specific gravity, and that a light timber would naturally be 

 chosen for the experiment. The discrepancy appears to me to be far too large 

 to admit of such an explanation. Had the board been of ordinary Scotch 

 pine, the indicator ought to have shown more than 3iBbs. 4ozs. pressure on the 

 balance, and even had the common Canadian yellow pine been used it could 

 hardly have shown less than 3S)S. Moreover, it is evident fi'om the context 



* For a full report of this paper see " Otago Daily Times," November, 1S7I. The article 

 by Mr. Crookes referred to appeared in the "Quart. Journ. of Science" for July, 1871. 



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