"Lecture Demonstration" is a

science fiction Science fiction (sometimes shortened to Sci-Fi or SF) is a genre of speculative fiction which typically deals with imagination, imaginative and futuristic concepts such as advanced science and technology, space exploration, time travel, Paral ...

short story A short story is a piece of prose fiction that typically can be read in one sitting and focuses on a self-contained incident or series of linked incidents, with the intent of evoking a single effect or mood. The short story is one of the oldest t ...

by American writer

Hal Clement Harry Clement Stubbs (May 30, 1922 – October 29, 2003), better known by the pen name Hal Clement, was an American science fiction writer and a leader of the hard science fiction subgenre. He also painted astronomically oriented artworks und ...

. It was first published in '' Astounding: The John W Campbell Memorial Anthology'' in 1973.

Plot introduction

The story is set on the planet

Mesklin Mesklin is a fictional supergiant planet created by Hal Clement and used in a number of his hard science fiction stories. It is distinctive for the interaction of its strong gravity with the centrifugal force due to its fast rotation, origina ...

as used in the author's novel ''

Mission of Gravity ''Mission of Gravity'' is a science fiction novel by American writer Hal Clement. The novel was serialized in ''Astounding Science Fiction'' magazine in April–July 1953. Its first hardcover book publication was in 1954, and it was first publi ...

'', but in an earlier period when the College established by the Terrestrials is still being set up and the teachers as well as the students are still learning.

Plot summary

Dr LaVerne, a teacher with the College, takes a party of Mesklinite students on a geological expedition. Whilst examining a layer of rock, it collapses. Teacher and students fall into a cavern. They are unable to climb out; the limiting factor is time, as the teacher is enclosed in a suit with a finite

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as we ...

supply. The students and teacher discuss various possibilities until they realise that they can raise the melting point of the surrounding

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogeno ...

'snow' to the point where it solidifies. They climb out to safety. 1973 short stories Science fiction short stories {{1970s-sf-story-stub