On July 3, 1886, Karl Benz unveils the Benz Patent-Motorwagen, widely regarded as the first automobiles to integrate an internal combustion engine with a chassis. This groundbreaking invention would go on to revolutionize transportation and society as a whole.

Karl Benz, a German mechanical engineer, had been working on various designs for horseless carriages since 1878. His early attempts included a two-stroke gas engine and a four-stroke engine based on Nicolaus Otto's design. However, it was the three-wheeled Benz Patent-Motorwagen that would make history.

The Motorwagen featured a single-cylinder four-stroke engine, which produced about 0.75 horsepower and reached a top speed of approximately 10 miles per hour (16 km/h). The engine was mounted horizontally at the rear, with its crankshaft aligned with the longitudinal axis of the vehicle. This design became known as the "boxer" engine configuration.

Other innovative features of the Motorwagen included:
1. An electric ignition system with a battery, coil, and spark plug
2. A differential gear for the rear wheels
3. A water-cooled engine to prevent overheating
4. A throttle valve to control engine speed
5. A brake for the rear wheels

The first public demonstration of the Benz Patent-Motorwagen took place on the Ringstrasse in Mannheim, Germany, on July 3, 1886. This event marked the beginning of the automobile era and paved the way for future advancements in transportation technology.

Interestingly, Karl Benz's wife, Bertha Benz, played a crucial role in popularizing the Motorwagen. In August 1888, without her husband's knowledge, Bertha and their two sons embarked on the first long-distance automobile journey in history. They traveled approximately 106 kilometers (66 miles) round-trip from Mannheim to Pforzheim, demonstrating the practicality and reliability of the automobile.

The Benz Patent-Motorwagen's unveiling on July 3, 1886, was a pivotal moment in the history of science and technology. It laid the foundation for the development of the modern automobile industry and transformed the way people travel, ultimately shaping the world we live in today.