216 



Mr. A. Le Sueur on the 



[Feb. 17, 



in contact. The mischief may possibly be seated in the corpora quadri- 

 gemina or geniculata, or even in the cerebellnm itself. 



As to the nature of the mischief in the brain, it is difficult to do more 

 than hazard guesses. Is it a temporary suspension of function among the 

 nerve-cells of the visual sensorium, due to vascular congestion, and relieved 

 by the relief of that congestion P Does the headache tell of the further 

 propagation of the nervous disturbance into parts of the brain where 

 disturbance is ache, as in the visual tract disturbance is abnormal sensation 

 of light ? And the detriment to speech and hearing, — does it mean exten- 

 sion of the same disturbance still further into the regions of brain-sub- 

 stance appropriate to those functions ? Or is the attack in any way analo- 

 gous to a fit of epilepsy ? 



The phenomena are so definite and so localized, and their course is so 

 regular, that we can hardly avoid the conviction that their cause is equally 

 definite and equally localized : and it is difficult to admit so vagne an 

 agent as nervous sympathy with gastric derangement, except as acting 

 through the medium of some secondary local manifestation in the brain. 



II. ' Account of the Great Melbourne Telescope from April 1868 

 to its commencement of operations in Australia in 1869/' By 

 Albert Le Sueur. Received January 8, 1870. Communi- 

 cated by the President. 



A description of the great Melbourne reflector, and its history, up to the 

 time of inspection by the Committee, have been communicated to the 

 Royal Society ; the following additional account of the doings connected 

 therewith since the instrument was consigned to my care may be of in- 

 terest to the Society. 



Mr. Grubb commenced taking down the telescope at the end of April 

 1868 ; this was accomplished in no great length of time, and without any 

 difficulty. The specula (by the advice of Mr. Lassell, who had found 

 this method answer perfectly) were coated ever with shellac varnish to pre- 

 vent oxidation on the voyage out ; they were then protected in their cells 

 and on their lever supports by strong double wood casings, and the other 

 parts of the telescope and machinery cased or otherwise protected. The 

 only casualty which there seemed to be any reason to fear could give rise 

 to any serious consequences was a tilting over of the speculum cases : 

 their great weight was, perhaps, a sufficient guarantee from such an event : 

 it was nevertheless thought prudent that the telescope, and machinery gene- 

 rally, should not be left entirely to the tender mercies of the shipping 

 and crane labourers ; I was therefore present at the shipping in Dublin on 

 board a steam-tug hired for the purpose, and at the transshipment in Liver- 

 pool, on board the 'Empress of the Seas.' 



Both these operations were performed satisfactorily, and without any 

 serious casualty. 



