. >> host: we hear from politicians, there petroski. we need more sign, technology, someone in the field. >> host: that is another tough question because there are two sides to it. engineers themselves a real people are engineers. there's more pay for engineers. so there is a pressure to keep numbers down scarce see with what the market determine. those who employ engineers would like to keep price down so they want more engineers. in the whole i think it is hard to do their question. specific cases where you have a certain kind of engineer with a certain task that there might be one correct answer rather than another. generally speaking, i am hesitant to say that necessarily needs more engineers. >> host: has technology in the last 30 years changed professionally? >> guest: i think just about every professionally. rise of the internet, computer modeling, not that these things didn't exist 30 years ago. it is just that they have become so pervasive. here it duke we had a freestanding engineering library 30 years ago. unless i use to lov

so that prompted me to really get going. >> host: finally professor petroski what's on the cover of "to forgive design"? >> guest: listen in shersinger story. that's a carton of eggs. it's a close-up of a carton of eggs. when i was first presented with the coverage by the publisher i thought this book is really not about eggs. it's about the good things like bridges and a horizon. i do have a whole chapter in their in which i talk about some things are meant to be broken like eggs for instance. the matrix designed for an egg is brilliant. it contains the shape until the check is ready to break out of it but at the same time from the external point of view the egg is a very wonderful package because it is very hard to crack on the outside just by let's say sitting on it and trying to hatch it. >> host: henry petroski professor of civil engineering and a professor of history here at duke university. you are watching booktv on c-span2's. >> i have a general philosophy that i'm approaching on all issues and it starts with the basic premise with which i approach editing. economic freedom a

joining us is professor henry petroski.ofessor petroski, what do you do for a living besides teach it to? what is your background? >> guest: my background is mostly academic. about 20 or 30 years ago i began writing about engineering, increasingly books. since then, that is a principal occupation, lecturing and generally doing a lot of thinking about engineering. >> host: what is engineering? >> guest: that's a good question. that is really what motivated my first book. i packed this as an engineer and if a neighbor asked me what is engineering, i really didn't have any there. so i thought the best way to develop would be too made up of. i found readiness by best way of thinking. so my first book is what is engineering and i have to admit i didn't go in to 200 i say really was a mean when i pressure on their engineers, some people confuse it with science and say it's just a branch of science or applied science. it is a

assessor petroski what do you do for a living besides teach at duke? what is your background?guest: my background is engineering, mostly academic but about 20 or 30 years ago i began to write about engineering, first essays but increasingly books. since then that has been my principle occupation is to write about engineering and lecture on books about engineering and generally doing a lot of thinking about engineering. >> host: what is engineering? >> guest: that's a good question and that is what motivated my first book. i have taught engineering. i registered as an engineer and if the neighbor interviewer asked me i've really didn't have a good answer. i thought the best way to develop an answer would be to write a book. i found that writing is my best way of thinking and understanding. my first book the working title was what is engineering. i had to admit i didn't go into it with any preconceived definition or understanding. i really was confused and i found when i would pressure other engineers it's a very confusing subject. some people confuse it with science and say eng

. >> hold on, tony, chad, we have another storm chaser joining us, jeff petroski, what is it like where you are? >> reporter: well, wolf, we had the first tornado touch down northwest of aurora about 45 minutes ago. i tracked the circulation to the southwest side of the national airport about a mile south of the runway. it became rain-wrapped. and then we had a new tornado develop that was actually quite large. i have one south of the dia runway, that was on the ground for about two minutes. then it lifted. and then as that tornado lifted a new one came down, and i got a tornado on the ground right now. stand by. tornado is now on the ground, one mile, tornado on the ground, again, three and a half southeast of dia airport, moving rapidly at 40 miles an hour. 100 yards wide, white cone, probably 65 miles an hour, accelerating to the north. right in front of me about half a mile moving north at 60 miles an hour. a round circulation. there it is, large tornado four miles southeast of the airport moving tracking southeast, moving east-northeast around the circulation. that was northwest of