He spent hours swimming in the Thames trying to develop an improved diving bell.  
In one text, this man proposed that the Earth contained a "luminous effluvium".  He spent hours swimming in the Thames trying to develop an improved diving bell.  This scientist's attempts to figure out the age of the Earth by measuring the saltiness of the oceans was one of the factors that caused his one-time protÃ©gÃ© John Flamsteed to try to blackball his appointment to the Savilian Chair of Geometry at Oxford.  This man tallied up death records from Breslau to create some of the first (*) actuarial tables.  He published the first magnetic charts of the oceans and also published Newton's Principia Mathematica.  He requested that future scientists carefully observe the 1761 transit of Venus in order to accurately measure the distance from the Earth to the Sun.  For 10 points, name this English scientist who predicted the 1758 return of a namesake comet.
In one text, this man proposed that the Earth contained a "luminous effluvium".  
Edmond Halley