First printings of two landmark papers in the history of science:

John Michell's 1784 paper containing the first discussion of the concept of black holes
and Henry Cavendish's experiments to determine the composition of water

"If the semi-diameter of a sphere of the same density as the Sun were to exceed that of the Sun in the proportion of 500 to 1, a body falling from an infinite height towards it would have acquired at its surface greater velocity than that of light, and consequently supposing light to be attracted by the same force in proportion to its vis inertiae (inertial mass), with other bodies, all light emitted from such a body would be made to return towards it by its own proper gravity." 

-John Michell on the concept of black holes

"By this means upwards of 135 grains of water were condensed in the cylinder, which had no taste nor smell, and which left no sensible sediment when evaporated to dryness; neither did it yield any pungent smell during the evaporation; in short, it seemed pure water." 

-Henry Cavendish on the composition of water

First printings of two landmark scientific papers: John Michell's discussion of the concept of a black hole and Henry Cavendish's experiments to determine the composition of water.

John Michell and the idea of a black hole:

"A black hole is a volume of space where gravity is so strong that nothing, not even light, can escape from it. This astonishing idea was first announced in 1783 by John Michell, an English country parson....  The idea came to him in 1783 while considering a hypothetical method to determine the mass of a star. Michell accepted Newton’s theory that light consists of small material particles. He reasoned that such particles, emerging from the surface of a star, would have their speed reduced by the star’s gravitational pull, just like projectiles fired upward from the Earth. By measuring the reduction in the speed of the light from a given star, he thought it might be possible to calculate the star’s mass.

"Michell asked himself how large this effect could be. He knew that any projectile must move faster than a certain critical speed to escape from a star’s gravitational embrace. This 'escape velocity' depends only on the size and mass of the star. What would happen if a star’s gravity were so strong that its escape velocity exceeded the speed of light? Michell realized that the light would have to fall back to the surface. He knew the approximate speed of light, which Ole Roemer had found in the previous century. So it was easy for Michell to calculate that the escape velocity would exceed the speed of light on a star more than 500 times the size of the Sun, assuming the same average density. Light cannot escape from such a body, which would, therefore, be invisible to the outside world. Today we would call it a black hole...  This concept was so far ahead of its time that it made little impression" until it was rediscovered by Einstein in the 20th century. "Michell suggested that we might detect invisible black holes if some of them had luminous stars revolving around them. In fact, this is one method used by astronomers today to infer the existence of black holes. We have observed numerous systems in which matter, whether gas clouds or entire stars, is moving so fast that only the concentrated mass of a black hole could be responsible for it" (Soter and deGrasse Tyson, ed., Cosmic Horizons).

Henry Cavendish's discovery of the composition of water:

"Published in 1784 under the title Experiments on Air, [Cavendish's paper] described his discovery that water could be made by combining hydrogen and oxygen. After Priestley discovered 'dephlogisticated air' (oxygen), Cavendish began to experiment with the gas. In one celebrated experiment he mixed air and hydrogen in a long glass cylinder and caused the hydrogen to burn. He found that the water that condensed in the cylinder had no taste or smell and that no sediment was formed when it was evaporated. He had produced pure water. This was followed by experiments in which hydrogen and oxygen were mixed in a large glass globe and exploded with an electric spark. Again, water was produced. Cavendish also obtained quantitative results, finding that water was a combination of two volumes of hydrogen and one volume of oxygen. 

"Cavendish didn't realize that he had shown that water was a compound of hydrogen and oxygen and therefore not an element. He was hobbled by the phlogiston theory, the only theory that chemistry then had. He concluded that hydrogen was water saturated with phlogiston and that oxygen was water from which all the phlogiston was removed. When they were combined, of course water was produced. Though his conclusions were erroneous, Cavendish had performed a crucial experiment that put another small nail into the coffin of the still widely accepted four-element theory. Although he misinterpreted his results, he had performed one of the crucial experiments in the history of chemistry" (Richard Morris, The Last Sorcerers). 

Very small embossed stamp on general title; text generally clean with only occasional light foxing. A most important scientific volume, handsomely bound in contemporary calf.