Snowflake unlikely that any two snowflakes are alike due to the estimated 10 (10 quintillion) water molecules which make up a typical snowflake, which grow at different rates and in different patterns depending on the changing temperature and humidity within the atmosphere that the snowflake falls through on its way to the ground. Snowflakes that look identical, but may vary at the molecular level, have been grown under controlled conditions. Although snowflakes are never completely symmetrical, a non-aggregated snowflake often grows so as to exhibit an approximation of six-fold radial symmetry. The symmetry gets started due to the hexagonal crystalline structure
At Home: A Short History of Private Life home, but a venue for Bryson to present each of a series of historical events as a "well-turned story, a mildly humorous aside, a colourful anecdote". Historian Judith Flanders said that "occasionally the book seems to have better jokes than it does a sense of history" but still called the book a "treasure". Another reviewer noted that one with "any interest in furniture, food, fashion, architecture, energy or world history ... (will have) stumbled across some (or all) of the information Bryson has on offer (because) countless books have been written on every subject covered in "At Home"; many are